What was the most significant event on August 12 during the U.S. Civil War?

In 1864 the USS (formerly CSS) Tennessee had her smokestack replaced and other damage repaired, began her new career in the US Navy as she got up steam on August 12, 1864.
Below are a number of journal entries from 1863 and 1864 which shed light on what life was like for soldiers and civilians – the good, the bad and the ugly. In 1861, President Lincoln proclaims a National Fast Day for the last Thursday in September. In 1864 Walt Whitman encounters Abraham Lincoln.
Monday, August 12, 1861: Lincoln proclaims a National Fast Day. On this day in 1861, Abraham Lincoln proclaimed a nation fast day on the last Thursday of September. Proclamation of a National Fast Day
By the President of the United States of America: “A Proclamation. Whereas a joint Committee of both Houses of Congress has waited on the President of the United States, and requested him to "recommend a day of public humiliation, prayer and fasting, to be observed by the people of the United States with religious solemnities, and the offering of fervent supplications to Almighty God for the safety and welfare of these States, His blessings on their arms, and a speedy restoration of peace:"---
And whereas it is fit and becoming in all people, at all times, to acknowledge and revere the Supreme Government of God; to bow in humble submission to his chastisements; to confess and deplore their sins and transgressions in the full conviction that the fear of the Lord is the beginning of wisdom; and to pray, with all fervency and contrition, for the pardon of their past offences, and for a blessing upon their present and prospective action: “And whereas, when our own beloved Country, once, by the blessing of God, united, prosperous and happy, is now afflicted with faction and civil war, it is peculiarly fit for us to recognize the hand of God in this terrible visitation, and in sorrowful remembrance of our own faults and crimes as a nation and as individuals, to humble ourselves before Him, and to pray for His mercy,---to pray that we may be spared further punishment, though most justly deserved; that our arms may be blessed and made effectual for the re-establishment of law, order and peace, throughout the wide extent of our country; and that the inestimable boon of civil and religious liberty, earned under His guidance and blessing, by the labors and sufferings of our fathers, may be restored in all its original excellence: “Therefore, I, Abraham Lincoln, President of the United States, do appoint the last Thursday in September next, as a day of humiliation, prayer and fasting for all the people of the nation. And I do earnestly recommend to all the People, and especially to all ministers and teachers of religion of all denominations, and to all heads of families, to observe and keep that day according to their several creeds and modes of worship, in all humility and with all religious solemnity, to the end that the united prayer of the nation may ascend to the Throne of Grace and bring down plentiful blessings upon our Country. In testimony whereof, I have hereunto set my hand, and caused the Seal of the United States to be affixed, this 12th. [L.S.] day of August a.d. 1861, and of the Independence of the United States of America the 86th.
Abraham Lincoln, By the President: ABRAHAM LINCOLN. WILLIAM H. SEWARD, Secretary of State.”
Wednesday, August 12, 1863: “George Templeton Strong, following up on his thoughts on the meaning of the war, makes a prophetic statement on the future: “We hardly appreciate, even yet, the magnitude of this war, the issues that depend on its result, the importance of the chapter in the world’s history that we are helping to write. In our hearts we esteem the struggle as the London Times does, or pretends to. God forgive our blindness! It is the struggle of two hostile and irreconcilable systems of society for the rule of this continent. Since Mahometanism and Christendom met in battle this side of the Pyrenees, there has been no struggle so momentous for mankind. I think that Grant and Rosecrans, Lee and Stonewall Jackson and Joe Johnston, and all the others, will be more conspicuous and better known to students of history A.D. 1963 than Wallenstein and Gustavus, Condé, Napoleon, Frederick, Wellington, and the late Lord Raglan; not as greater generals, but as fighting on a larger field and in a greater cause than any of them. So will our great-great-grandchildren look back on them a century hence, whatever be the result.”
Wednesday, August 12, 1863: The Diary of John B. Jones. Wartime Richmond, Virginia. On this day 150 years ago, Confederate war clerk John B. Jones wrote of food supplies, gold being sent out of the Confederacy on blockade runners, and reports of the Battle of Gettysburg, more than a month earlier. “August 12th.—Letters from Georgia to-day assure the government that the grain crops of that State will afford a surplus sufficient for the army, cavalry and all, for 12 months.
Also one from P. Clayton, late Assistant Secretary of the Treasury, censuring the commissary agents in Georgia, who are sent thither from other States, who insult the farmers and encourage speculation.
Mr. Memminger is shipping gold from Wilmington, $20,000 by each steamer, to Bermuda and Nassau. Why is this? Cotton is quite as good as gold, and there are thousands of millions worth of that in the country, which Mr. Memminger might buy, certainly might have bought for Confederate notes, but, in his peculiar wisdom, he would not. And now, the great financier is shipping gold out of the country, thinking, perhaps, it may arrest the depreciation of paper money!
Col. Northrop, Commissary-General, is still urging a diminution of rations, and as our soldiers taken by the enemy fare badly in the North, and as the enemy make a point of destroying all the crops they can when they invade us, and even destroy our agricultural implements and teams, he proposes, in retaliation, to stop meat rations altogether to prisoners in our hands, and give them instead oat gruel, corn-meal gruel, and pea soup, soft hominy, and bread. This the Secretary will not agree to, because the law says they shall have the same as our troops.
I read to-day Gen. Lee’s report of his operations (an outline) in June and July, embracing his campaign in Maryland and Pennsylvania.
The enemy could not be attacked advantageously opposite Fredericksburg, and hence he determined to draw him out of his position by relieving the lower valley of the Shenandoah, and, if practicable, transfer the scene of hostilities north of the Potomac.
The movement began on the 3d of June. The divisions of McLaws and Hood (Longstreet’s) marched for Culpepper C. H. They were followed on the 4th and 5th by Ewell’s corps, A. P. Hill’s still occupying our lines at Fredericksburg.
When the enemy discovered the movement (on the 5th), he sent an army corps across the Rappahannock, but this did not arrest Longstreet and Ewell, who reached Culpepper C. H. on the 8th, where they found Gen. Stuart and his cavalry. On the 9th the enemy’s cavalry and a strong force of infantry crossed the Rappahannock and attacked Gen. Stuart, but they were beaten back, after fighting all day, with heavy loss, including 400 prisoners, 3 pieces artillery, and several colors.
Gens. Jenkins and Imboden had been sent in advance, the latter against Romney, to cover the former’s movement against Winchester, and both were in position when Ewell left Culpepper C. H. on the 16th.
Gen. Early stormed the enemy’s works at Winchester on the 14th, and the whole army of Milroy was captured or dispersed.
Gen. Rhodes, on the same day, took Martinsburg, Va., capturing 700 prisoners, 5 pieces artillery, and a large supply of stores.
More than 4000 prisoners were taken at Winchester; 29 pieces artillery; 270 wagons and ambulances; 400 horses, besides a large amount of military stores.
Precisely at this time the enemy disappeared from Fredericksburg, seemingly designing to take a position to cover Washington.
Gen. Stuart, in several engagements, took 400 more prisoners, etc.
Meantime, Gen. Ewell, with Gen. Jenkins’s cavalry, etc., penetrated Maryland, and Pennsylvania as far as Chambersburg.
On the 24th, Lt.-Gens. Longstreet and Hill marched to the Potomac, the former crossing at Williamsport and the latter at Shepherdstown, uniting at Hagerstown, Md., advancing into Pennsylvania, and encamping near Chambersburg on the 27th.
Ewell’s corps advanced as far as York and Carlisle, to keep the enemy out of the mountains, and to keep our communications open.
Gen. Imboden destroyed all the important bridges of the Baltimore and Ohio Railroad from Martinsburg to Cumberland, damaging the Chesapeake and Ohio Canal.
Preparations were made to march upon Harrisburg, when information was received of the approach of the army of the enemy, menacing communications with the Potomac, necessitating a concentration of our army at Gettysburg.
Hill became engaged with a superior force of the enemy on the 1st July, but Ewell, coming up by the Harrisburg road, participated in the engagement, and the enemy were driven through Gettysburg with heavy loss, including about 5000 prisoners and several pieces of artillery.
The enemy retired to a high range of hills, south and east of the town.
On the 2d, Gen. Ewell occupied the left, Gen. Hill the Center, and Gen. Longstreet the right.
Longstreet got possession of the enemy’s position in front of his corps after a severe struggle; Ewell also carried some strong positions. The battle ceased at dark.
The next day, 3d July, our batteries were moved forward to the positions we had gained, and it was determined to renew the attack.
Meantime the enemy had strengthened his line. The battle raged with great violence in the afternoon, until sunset. We got possession of some of the enemy’s batteries, but our ammunition failing, our troops were compelled to relinquish them, and fall back to their original position with severe loss.
Our troops (the general says) behaved well in the protracted and sanguinary conflict, accomplishing all that was practicable.
The strong position of the enemy, and reduction of his ammunition, rendered it inexpedient for Gen. Lee to continue longer where he was. Such of the wounded as could be moved, and part of the arms collected on the field, were ordered to Williamsport.
His army remained at Gettysburg during the 4th, and began to retire at night, taking with it about 4000 prisoners, nearly 2000 having been previously paroled. The enemy’s wounded that fell into his hands were left behind.
He reached Williamsport without molestation, losing but few wagons, etc., and arrived at Hagerstown 7th July.
The Potomac was much swollen by recent rains, that had fallen incessantly ever since he had crossed it, and was unfordable.
The enemy had not yet appeared, until the 12th, when, instead of attacking, Meade fortified his lines.
On the 13th Gen. Lee crossed at Falling Waters, the river subsiding, by fords and a bridge, without loss, the enemy making no interruption. Only some stragglers, sleeping, fell into the hands of the enemy.”
Friday, August 12, 1864: Walt Whitman encounters Abraham Lincoln. On this day 150 years ago, poet Walt Whitman encountered Abraham Lincoln and his cavalry escort on the road and left this description of Lincoln. “August 12th.—I SEE the President almost every day, as I happen to live where he passes to or from his lodgings out of town. He never sleeps at the White House during the hot season, but has quarters at a healthy location some three miles north of the city, the Soldiers’ home, a United States military establishment. I saw him this morning about 8 1/2 coming in to business, riding on Vermont avenue, near L street. He always has a company of twenty-five or thirty cavalry, with sabres drawn and held upright over their shoulders. They say this guard was against his personal wish, but he let his counselors have their way. The party makes no great show in uniform or horses. Mr. Lincoln on the saddle generally rides a good-sized, easy-going gray horse, is dress’d in plain black, somewhat rusty and dusty, wears a black stiff hat, and looks about as ordinary in attire, &c., as the commonest man. A lieutenant, with yellow straps, rides at his left, and following behind, two by two, come the cavalry men, in their yellow-striped jackets. They are generally going at a slow trot, as that is the pace set them by the one they wait upon. The sabres and accoutrements clank, and the entirely unornamental cortège as it trots towards Lafayette square arouses no sensation, only some curious stranger stops and gazes. I see very plainly ABRAHAM LINCOLN’S dark brown face, with the deep-cut lines, the eyes, always to me with a deep latent sadness in the expression. We have got so that we exchange bows, and very cordial ones. Sometimes the President goes and comes in an open barouche. The cavalry always accompany him, with drawn sabres. Often I notice as he goes out evenings—and sometimes in the morning, when he returns early—he turns off and halts at the large and handsome residence of the Secretary of War, on K street, and holds conference there. If in his barouche, I can see from my window he does not alight, but sits in his vehicle, and Mr. Stanton comes out to attend him. Sometimes one of his sons, a boy of ten or twelve, accompanies him, riding at his right on a pony. Earlier in the summer I occasionally saw the President and his wife, toward the latter part of the afternoon, out in a barouche, on a pleasure ride through the city. Mrs. Lincoln was dress’d in complete black, with a long crape veil. The equipage is of the plainest kind, only two horses, and they nothing extra. They pass’d me once very close, and I saw the President in the face fully, as they were moving slowly, and his look, though abstracted, happen’d to be directed steadily in my eye. He bow’d and smiled, but far beneath his smile I noticed well the expression I have alluded to. None of the artists or pictures has caught the deep, though subtle and indirect expression of this man’s face. There is something else there. One of the great portrait painters of two or three centuries ago is needed.”

Pictures: 1863-08 Exploding Shell at Fort Sumter; 1864 TALAHASSEE AT HALIFAX; 1863-08 Captain Semmes, on board the Alabama in August 1863 with his 110-pounder Blakely; 1864 Dictatorcrop

A. Monday, August 12, 1861: Fort Davis, Texas. A 16-man Confederate detachment rode into an ambush set by Chief Nicholas of the Mescalero Apaches in the Big Bend country south of Fort Davis. The only person from the detachment to escape was the Mexican guide.
B. Tuesday, August 12, 1862: Galatin, Tennessee. Col. John Hunt Morgan’s cavalry raiders swept into Gallatin, a town on the vital railroad between Nashville and the Union supply center at Louisville. After the Confederates had captured the local Union garrison, burned down the railroad depot and destroyed some of its trestles. Morgan's men set fire to a captured Union supply train, which they had loaded up with hay, and pushed the train into the 800-foot railroad tunnel that had been cut through a mountain, north of the town. Inside the tunnel, the wooden support beams caught fire and burned until they collapsed. This action closed the railroad and tunnel for months to come and destroyed the South Tunnel on the railroad
C. Wednesday, August 12, 1863: Siege of Charleston Harbor: Federal batteries on Morris Island start a ranging barrage, measuring the distance to various Confederate targets, that will last four days. ““They were only practice shots. They came from Parrott guns, which were named for their inventor and not tropical birds. These were special Parrott guns though, heavier in caliber than normal and rifled inside the barrel for greater accuracy and range. The Federal forces had finally gotten them ashore on Morris Island in Charleston Harbor and installed them on their mountings in the sand. They fired off calibration shots today, intending only to test the aim of the weapons. They blew holes in the brick walls of Ft. Sumter with these test shots.” Federal batteries on Morris Island open up a "ranging" barrage that will last four days.
D. Friday, August 12, 1864: In Mobile Bay, the USS Tennessee (formerly Confederate navy gunboat Tennessee) having had her smokestack replaced and other damage repaired, began her new career in the US Navy. Meanwhile the Confederate raider, CSS Tallahassee, captured six more Federal vessels off the coast of New Jersey and New York, causing alarm up and down the eastern seaboard.

1. Monday, August 12, 1861: Lincoln proclaims a National Fast Day. On this day in 1861, Abraham Lincoln proclaimed a nation fast day on the last Thursday of September. Proclamation of a National Fast Day
By the President of the United States of America: “A Proclamation. Whereas a joint Committee of both Houses of Congress has waited on the President of the United States, and requested him to "recommend a day of public humiliation, prayer and fasting, to be observed by the people of the United States with religious solemnities, and the offering of fervent supplications to Almighty God for the safety and welfare of these States, His blessings on their arms, and a speedy restoration of peace:"---
And whereas it is fit and becoming in all people, at all times, to acknowledge and revere the Supreme Government of God; to bow in humble submission to his chastisements; to confess and deplore their sins and transgressions in the full conviction that the fear of the Lord is the beginning of wisdom; and to pray, with all fervency and contrition, for the pardon of their past offences, and for a blessing upon their present and prospective action: “And whereas, when our own beloved Country, once, by the blessing of God, united, prosperous and happy, is now afflicted with faction and civil war, it is peculiarly fit for us to recognize the hand of God in this terrible visitation, and in sorrowful remembrance of our own faults and crimes as a nation and as individuals, to humble ourselves before Him, and to pray for His mercy,---to pray that we may be spared further punishment, though most justly deserved; that our arms may be blessed and made effectual for the re-establishment of law, order and peace, throughout the wide extent of our country; and that the inestimable boon of civil and religious liberty, earned under His guidance and blessing, by the labors and sufferings of our fathers, may be restored in all its original excellence: “Therefore, I, Abraham Lincoln, President of the United States, do appoint the last Thursday in September next, as a day of humiliation, prayer and fasting for all the people of the nation. And I do earnestly recommend to all the People, and especially to all ministers and teachers of religion of all denominations, and to all heads of families, to observe and keep that day according to their several creeds and modes of worship, in all humility and with all religious solemnity, to the end that the united prayer of the nation may ascend to the Throne of Grace and bring down plentiful blessings upon our Country. In testimony whereof, I have hereunto set my hand, and caused the Seal of the United States to be affixed, this 12th. [L.S.] day of August a.d. 1861, and of the Independence of the United States of America the 86th.
Abraham Lincoln, By the President: ABRAHAM LINCOLN. WILLIAM H. SEWARD, Secretary of State.”
Abraham Lincoln was not the most religious of men when the war started, though as the war progressed he began to lean more and more on a new found faith. As for the National Day of Fast: it never caught on--but another Lincoln innovation--Thanksgiving--would become an annual tradition. Americans would rather celebrate their blessings than mortify their flesh, or so it would seem.
http://www.civilwar-online.com/search?q=August+12%2C+1861
2. Tuesday, August 12, 1862: Manassas/Second Manassas Campaign: At Cedar Run, General Pope advances, to find his foes gone. The Federals are somewhat shocked, as the following telegrams from Year of Glory show: Headquarters Army of Virginia, Cedar Mountain, August 12, 1862 – 7.30 a.m. Major-General Halleck: “The enemy has retreated under cover of the night. His rear is now crossing the Rapidan toward Orange Court-House. Our cavalry and artillery are in pursuit. I shall follow with the infantry as far as the Rapidan. Will keep you advised. JNO. POPE, Major-General, Commanding.
Washington, D.C., August 12, 1862. Major-General Pope: “Beware of a snare. Feigned retreats are secesh tactics.” H.W. Halleck, General-in-Chief.
Signal Station at Headquarters, August 12, 1862 – 11 a.m. General McDowell: “Please send me some infantry. The enemy are trying to turn our left.” Duffie, Colonel.
Signal Station, Headquarters, August 12, 1862 – 12 m. General Pope: “General Sigel’s cavalry fired on us. It was not the enemy.” A.N. Duffie, Colonel.
https://bjdeming.com/2012/09/17/the-american-civil-war-150th-anniversary-august-6-12-1862/
3. Tuesday, August 12, 1862: Harrison’s Landing, Virginia: McClellan learns from his cavalry commander that Richmond’s defense is down to roughly 36,000 men. He telegraphs General Halleck, offering to attack Richmond, but only with reinforcements. Halleck writes a lengthy letter to McClellan that includes this: “I deem it my duty to write you confidentially that the administration is greatly dissatisfied with the slowness of your operations . . . So strong is this dissatisfaction that I have several times been asked to recommend some officer to take your place . . . the Government will expect an active campaign by the troops under your command, and that unless that is done the present dissatisfaction is so great your friends here will not be able to prevent a change being ordered.”
https://bjdeming.com/2012/09/17/the-american-civil-war-150th-anniversary-august-6-12-1862/
4. Tuesday, August 12, 1862: In Bolivar, Tennessee, John Houston Bills of “The Pillars” writes: “Some 20 of our Citizens who have not taken the oath of Allegiance are arrested yesterday and 15 of them sent north by the train this morning. Amongst them Jo Neilson & Jerome Hill.”
https://sites.google.com/site/civilwarhardemancotn/departments/department-b/part-seventy
5. Tuesday, August 12, 1862: Chattanooga Campaign of 1862: Halleck replies to Buell: “If the enemy are concentrating in East Tennessee you must move there and break them up. Go wherever the enemy is.” General Buell requests two divisions from Grant, in Corinth, Mississippi. Around dawn, CS General John Hunt Morgan and his cavalry appear in Gallatin, Tennessee, having slipped through picket lines and then captured the pickets and the town without a fight. “Lightning” Ellsworth gets on the telegraph and sends out false messages but fails this time to intercept any useful Union messages. The raiders destroy government stores and two freight train in town and then spread out to carry the damage further. Some go south to destroy the Pilot Knob Bridge, and others head for the Twin Tunnels, where they easily overpower the Federal guards and prepare to destroy Big South, one of the tunnels, by piling cross-ties inside the tunnel as an obstacle and then loading up flatcars with ties behind a locomotive, setting these alight and then sending the unmanned train racing into the tunnel, where it hits the obstacle and overturns. The resulting inferno burns through the tunnel supports, and some 800 feet of the tunnel collapses. The heat is so intense, it ignites an exposed coal seam in the bedrock. The raiders then tear up 600 feet of track south of Big South and burn a small bridge. It will be another 98 days before Buell can hope to be supplied from Nashville again.
https://bjdeming.com/2012/09/17/the-american-civil-war-150th-anniversary-august-6-12-1862/
6. Wednesday, August 12, 1863: “George Templeton Strong, following up on his thoughts on the meaning of the war, makes a prophetic statement on the future: “We hardly appreciate, even yet, the magnitude of this war, the issues that depend on its result, the importance of the chapter in the world’s history that we are helping to write. In our hearts we esteem the struggle as the London Times does, or pretends to. God forgive our blindness! It is the struggle of two hostile and irreconcilable systems of society for the rule of this continent. Since Mahometanism and Christendom met in battle this side of the Pyrenees, there has been no struggle so momentous for mankind. I think that Grant and Rosecrans, Lee and Stonewall Jackson and Joe Johnston, and all the others, will be more conspicuous and better known to students of history A.D. 1963 than Wallenstein and Gustavus, Condé, Napoleon, Frederick, Wellington, and the late Lord Raglan; not as greater generals, but as fighting on a larger field and in a greater cause than any of them. So will our great-great-grandchildren look back on them a century hence, whatever be the result.”
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=August+12%2C+1863
7. Wednesday, August 12, 1863: The Diary of John B. Jones. Wartime Richmond, Virginia. On this day 150 years ago, Confederate war clerk John B. Jones wrote of food supplies, gold being sent out of the Confederacy on blockade runners, and reports of the Battle of Gettysburg, more than a month earlier. “August 12th.—Letters from Georgia to-day assure the government that the grain crops of that State will afford a surplus sufficient for the army, cavalry and all, for 12 months.
Also one from P. Clayton, late Assistant Secretary of the Treasury, censuring the commissary agents in Georgia, who are sent thither from other States, who insult the farmers and encourage speculation.
Mr. Memminger is shipping gold from Wilmington, $20,000 by each steamer, to Bermuda and Nassau. Why is this? Cotton is quite as good as gold, and there are thousands of millions worth of that in the country, which Mr. Memminger might buy, certainly might have bought for Confederate notes, but, in his peculiar wisdom, he would not. And now, the great financier is shipping gold out of the country, thinking, perhaps, it may arrest the depreciation of paper money!
Col. Northrop, Commissary-General, is still urging a diminution of rations, and as our soldiers taken by the enemy fare badly in the North, and as the enemy make a point of destroying all the crops they can when they invade us, and even destroy our agricultural implements and teams, he proposes, in retaliation, to stop meat rations altogether to prisoners in our hands, and give them instead oat gruel, corn-meal gruel, and pea soup, soft hominy, and bread. This the Secretary will not agree to, because the law says they shall have the same as our troops.
I read to-day Gen. Lee’s report of his operations (an outline) in June and July, embracing his campaign in Maryland and Pennsylvania.
The enemy could not be attacked advantageously opposite Fredericksburg, and hence he determined to draw him out of his position by relieving the lower valley of the Shenandoah, and, if practicable, transfer the scene of hostilities north of the Potomac.
The movement began on the 3d of June. The divisions of McLaws and Hood (Longstreet’s) marched for Culpepper C. H. They were followed on the 4th and 5th by Ewell’s corps, A. P. Hill’s still occupying our lines at Fredericksburg.
When the enemy discovered the movement (on the 5th), he sent an army corps across the Rappahannock, but this did not arrest Longstreet and Ewell, who reached Culpepper C. H. on the 8th, where they found Gen. Stuart and his cavalry. On the 9th the enemy’s cavalry and a strong force of infantry crossed the Rappahannock and attacked Gen. Stuart, but they were beaten back, after fighting all day, with heavy loss, including 400 prisoners, 3 pieces artillery, and several colors.
Gens. Jenkins and Imboden had been sent in advance, the latter against Romney, to cover the former’s movement against Winchester, and both were in position when Ewell left Culpepper C. H. on the 16th.
Gen. Early stormed the enemy’s works at Winchester on the 14th, and the whole army of Milroy was captured or dispersed.
Gen. Rhodes, on the same day, took Martinsburg, Va., capturing 700 prisoners, 5 pieces artillery, and a large supply of stores.
More than 4000 prisoners were taken at Winchester; 29 pieces artillery; 270 wagons and ambulances; 400 horses, besides a large amount of military stores.
Precisely at this time the enemy disappeared from Fredericksburg, seemingly designing to take a position to cover Washington.
Gen. Stuart, in several engagements, took 400 more prisoners, etc.
Meantime, Gen. Ewell, with Gen. Jenkins’s cavalry, etc., penetrated Maryland, and Pennsylvania as far as Chambersburg.
On the 24th, Lt.-Gens. Longstreet and Hill marched to the Potomac, the former crossing at Williamsport and the latter at Shepherdstown, uniting at Hagerstown, Md., advancing into Pennsylvania, and encamping near Chambersburg on the 27th.
Ewell’s corps advanced as far as York and Carlisle, to keep the enemy out of the mountains, and to keep our communications open.
Gen. Imboden destroyed all the important bridges of the Baltimore and Ohio Railroad from Martinsburg to Cumberland, damaging the Chesapeake and Ohio Canal.
Preparations were made to march upon Harrisburg, when information was received of the approach of the army of the enemy, menacing communications with the Potomac, necessitating a concentration of our army at Gettysburg.
Hill became engaged with a superior force of the enemy on the 1st July, but Ewell, coming up by the Harrisburg road, participated in the engagement, and the enemy were driven through Gettysburg with heavy loss, including about 5000 prisoners and several pieces of artillery.
The enemy retired to a high range of hills, south and east of the town.
On the 2d, Gen. Ewell occupied the left, Gen. Hill the Center, and Gen. Longstreet the right.
Longstreet got possession of the enemy’s position in front of his corps after a severe struggle; Ewell also carried some strong positions. The battle ceased at dark.
The next day, 3d July, our batteries were moved forward to the positions we had gained, and it was determined to renew the attack.
Meantime the enemy had strengthened his line. The battle raged with great violence in the afternoon, until sunset. We got possession of some of the enemy’s batteries, but our ammunition failing, our troops were compelled to relinquish them, and fall back to their original position with severe loss.
Our troops (the general says) behaved well in the protracted and sanguinary conflict, accomplishing all that was practicable.
The strong position of the enemy, and reduction of his ammunition, rendered it inexpedient for Gen. Lee to continue longer where he was. Such of the wounded as could be moved, and part of the arms collected on the field, were ordered to Williamsport.
His army remained at Gettysburg during the 4th, and began to retire at night, taking with it about 4000 prisoners, nearly 2000 having been previously paroled. The enemy’s wounded that fell into his hands were left behind.
He reached Williamsport without molestation, losing but few wagons, etc., and arrived at Hagerstown 7th July.
The Potomac was much swollen by recent rains, that had fallen incessantly ever since he had crossed it, and was unfordable.
The enemy had not yet appeared, until the 12th, when, instead of attacking, Meade fortified his lines.
On the 13th Gen. Lee crossed at Falling Waters, the river subsiding, by fords and a bridge, without loss, the enemy making no interruption. Only some stragglers, sleeping, fell into the hands of the enemy.”
http://www.civilwar-online.com/search?q=August+12%2C+1863
8. Wednesday, August 12, 1863: The Diary of John B. Jones' diary touched on many interesting topics on this day.
1) Richmond's growing dependence on Georgia for food, which would place great strain on Confederate transportation and logistics.
2) One unintended consequence of the blockade is that it is causing gold to drain out of the Confederacy. As hard currency leaves the Confederate economy, inflation will destroy the value of Confederate paper currency.
3) The problem of feeding prisoners of war. This problem would only get worse as Southern attitudes towards Black troops was causing the prisoner exchange system to break down. Some Confederates are beginning to advocate deliberately starving Union prisoners.
4) The great length of time it took accurate news to make its way to headquarters from the battlefield. It took more than a month after the battle for John B. Jones in Richmond to piece together an accurate account of what had happened in Pennsylvania.
http://www.civilwar-online.com/search?q=August+12%2C+1863
9. Wednesday, August 12, 1863: A newspaper called the Missouri Democrat reports on rumors of the mistreatment of black troops captured by the Rebels of the torture and mutilation of white officers who had commanded black troops in battle: “REBEL BARBARISM-HOW THE OFFICERS OF THE NEGRO REGIMENTS AND THE NEGROES THEMSELVES WERE TREATED.
The following is given us upon the authority of Lieutenant Cole, of the Mississippi Marine Brigade: “The day after the battle of Milliken’s Bend, in June last, the Marine Brigade landed some 10 miles below the Bend, and attacked and routed the guerrillas which had been repulsed by our troops and the gunboats the day previous. Major Hubbard’s cavalry battalion, of the Marine Brigade, followed the retreating rebels to Tensas Bayou, and were horrified in the finding of skeletons of white officers commanding negro regiments, who had been captured by the rebels at Milliken’s Bend. In many cases these officers had been nailed to the trees and crucified; in this situation a fire was built around the tree, and they suffered a slow death from broiling. The charred and partially burned limbs were still fastened to the stakes. Other instances were noticed of charred skeletons of officers, which had been nailed to slabs, and the slabs placed against a house which was set on fire by the inhuman demons, the poor sufferers having been roasted alive until nothing was left but charred bones. Negro prisoners recaptured from the guerrillas confirmed these facts, which were amply corroborated by the bodies found, as above described. The negroes taken were to be resold into slavery, while the white officers were consumed by fire. Lieutenant Cole holds himself responsible for the truth of the statement.”
http://civilwarsesquicentdaily-wolfshield.blogspot.com/search?q=August+12%2C+1863
10. Friday, August 12, 1864: Hood's General Field Order No. 14. Southerners have long held a grudge against William Tecumseh Sherman for his destructive tactics, but most have forgotten the threat to Southern property posed by the Confederacy's own troops.
General John B. Hood's General Field Order No. 14 - August 12, 1864. In the Field, August 12, 1864 “I. The lawless seizure and destruction of private property by straggling soldiers in the rear and on the flanks of this army has become intolerable. It must come to an end. It is believed to be chargeable to worthless men, especially from mounted commands, who are odious alike to the citizen and the well-disposed soldier. Citizens and soldiers are, therefore, called upon to arrest and forward to the provost-marshal-general all persons guilty of wanton destruction or illegal seizure of property, that examples may be immediately made. The laws of war justify the execution of such offenders, and those laws shall govern.
II. Officers are held responsible that their men conduct themselves properly. In any cases where it is shown that an officer, high or low, has permitted or failed to take proper steps to prevent such depredations as those complained of herein, he shall be deprived of his commission.
III. Hereafter all cavalry horses must be branded. Division and brigade commanders will determine the manner so as to best designate the commands to which they belong. No purchase or exchange of horses will be permitted except by authority of the company and regimental commanders. In each case of such purchase or exchange the soldier must receive a written statement of the transaction. Any soldier otherwise introducing a horse into any command will be immediately arrested. General, field, and company officers are expected, and, are earnestly requested, to give this matter their attention. Officers failing must be arrested. In procuring forage, the least possible damage must be done the farmer. Too much attention cannot be given this. At best, he is compelled to suffer.
IV. Citizens are warned not to purchase from or exchange horses with soldiers, except when the authority for the transaction is previously had from the company and regimental commanders. Otherwise they may lose their property and will fail to receive the support of the military authorities.
By command of General Hood: A.P. Mason, Major and Assistant Adjutant-General.”
http://www.civilwar-online.com/search?q=August+12%2C+1864
11. Friday, August 12, 1864: Walt Whitman encounters Abraham Lincoln. On this day 150 years ago, poet Walt Whitman encountered Abraham Lincoln and his cavalry escort on the road and left this description of Lincoln. “August 12th.—I SEE the President almost every day, as I happen to live where he passes to or from his lodgings out of town. He never sleeps at the White House during the hot season, but has quarters at a healthy location some three miles north of the city, the Soldiers’ home, a United States military establishment. I saw him this morning about 8 1/2 coming in to business, riding on Vermont avenue, near L street. He always has a company of twenty-five or thirty cavalry, with sabres drawn and held upright over their shoulders. They say this guard was against his personal wish, but he let his counselors have their way. The party makes no great show in uniform or horses. Mr. Lincoln on the saddle generally rides a good-sized, easy-going gray horse, is dress’d in plain black, somewhat rusty and dusty, wears a black stiff hat, and looks about as ordinary in attire, &c., as the commonest man. A lieutenant, with yellow straps, rides at his left, and following behind, two by two, come the cavalry men, in their yellow-striped jackets. They are generally going at a slow trot, as that is the pace set them by the one they wait upon. The sabres and accoutrements clank, and the entirely unornamental cortège as it trots towards Lafayette square arouses no sensation, only some curious stranger stops and gazes. I see very plainly ABRAHAM LINCOLN’S dark brown face, with the deep-cut lines, the eyes, always to me with a deep latent sadness in the expression. We have got so that we exchange bows, and very cordial ones. Sometimes the President goes and comes in an open barouche. The cavalry always accompany him, with drawn sabres. Often I notice as he goes out evenings—and sometimes in the morning, when he returns early—he turns off and halts at the large and handsome residence of the Secretary of War, on K street, and holds conference there. If in his barouche, I can see from my window he does not alight, but sits in his vehicle, and Mr. Stanton comes out to attend him. Sometimes one of his sons, a boy of ten or twelve, accompanies him, riding at his right on a pony. Earlier in the summer I occasionally saw the President and his wife, toward the latter part of the afternoon, out in a barouche, on a pleasure ride through the city. Mrs. Lincoln was dress’d in complete black, with a long crape veil. The equipage is of the plainest kind, only two horses, and they nothing extra. They pass’d me once very close, and I saw the President in the face fully, as they were moving slowly, and his look, though abstracted, happen’d to be directed steadily in my eye. He bow’d and smiled, but far beneath his smile I noticed well the expression I have alluded to. None of the artists or pictures has caught the deep, though subtle and indirect expression of this man’s face. There is something else there. One of the great portrait painters of two or three centuries ago is needed.”
http://www.civilwar-online.com/search?q=August+12%2C+1864
12. Wednesday, August 12, 1863: the new “torpedo fish” boat General Beauregard requested from Mobile arrives by rail. It is named the H. L. Hunley after its designer, Horace Hunley, when the military takes control of the ship.
https://bjdeming.com/2013/08/12/the-american-civil-war-150th-anniversary-august-12-18-1863/
13. Friday, August 12, 1864: Confederate naval operations: “It was not uncommon for soldiers on both sides to be in the army despite having no great desire to be there. Perhaps they were drafted, or enlisted in an outburst of enthusiasm which they now regretted. When one of these soldiers was captured they might be offered freedom on the condition of joining the OTHER army. Such new recruits were said to have been ‘galvanized’, as in having a coat of a new color painted on the outside. The procedure did not just apply to men: the gunboat Tennessee, formerly of the Confederate navy, having had her smokestack replaced and other damage repaired, began her new career in the US Navy as she got up steam today.”
https://bjdeming.com/2014/08/10/the-american-civil-war-150th-anniversary-august-11-17-1864/
14. Friday, August 12, 1864: Siege of Atlanta. Per General Sherman: “On the 12th of August I heard of the success of Admiral Farragut in entering Mobile Bay, which was regarded as a most valuable auxiliary to our operations at Atlanta; and learned that I had been commissioned a major-general in the regular army, which was unexpected, and not desired until successful in the capture of Atlanta. These did not change the fact that we were held in check by the stubborn defense of the place, and a conviction was forced on my mind that our enemy would hold fast, even though every house in the town should be battered down by our artillery. It was evident that we most decoy him out to fight us on something like equal terms, or else, with the whole army, raise the siege and attack his communications.”
https://bjdeming.com/2014/08/10/the-american-civil-war-150th-anniversary-august-11-17-1864/
15. Friday, August 12, 1864: Mississippi operations: Skirmishing continues between Chalmers’ men and US pickets.
https://bjdeming.com/2014/08/10/the-american-civil-war-150th-anniversary-august-11-17-1864/
16. Friday, August 12, 1864: Shenandoah Valley operations, Early’s raid: General Grant warns General Sheridan that reinforcements may be on the way to Early.
https://bjdeming.com/2014/08/10/the-american-civil-war-150th-anniversary-august-11-17-1864/
17. Friday, August 12, 1864: Rebel guerrillas attack Yankees at Fredericksburg, Missouri but are driven off.
https://sites.google.com/site/civilwarhardemancotn/departments/1864/week-174
18. Friday, August 12, 1864: President Lincoln checks into Grant’s reaction to the possibility of becoming a presidential candidate. Grant (who will eventually become president in March 1869) says, “They can’t compel me to do it!”
https://bjdeming.com/2014/08/10/the-american-civil-war-150th-anniversary-august-11-17-1864/

A Monday, August 12, 1861: Fort Davis, Texas - On August 12, a 16-man Confederate detachment rode into an ambush set by Chief Nicholas of the Mescalero Apaches in the Big Bend country south of Fort Davis. The only person from the detachment to escape was the Mexican guide.
http://www.mycivilwar.com/battles/1861s.html
A+ Monday, August 12, 1861: Apache Indians attack Confederates in Texas and kill 15.
https://sites.google.com/site/civilwarhardemancotn/departments/department-a/part-eighteen
Monday, August 12, 1861: The Nashville “Union and American” reports the arrest of the Hon. Thomas A.R. Nelson has been arrested in Lee County, Virginia, and is expected to be tried for treason. Nelson was a staunch pro-Union southerner. He was elected to a second term in 1861 on the eve of the Civil War, but was arrested by Confederate authorities before he could take his seat.
https://sites.google.com/site/civilwarhardemancotn/departments/department-a/part-eighteen
Monday, August 12, 1861: Three new wooden gunboats, Tyler, Conestoga, and Lexington, arrive at Cairo, Illinois to cover operations until the ironclads are built.
https://sites.google.com/site/civilwarhardemancotn/departments/department-a/part-eighteen
B Tuesday, August 12, 1862: Galatin, Tennessee - On August 12, Confederate raiders under Col. John Hunt Morgan swept into Gallatin, a town on the vital railroad between Nashville and the Union supply center at Louisville. After the Confederates had captured the local Union garrison, burned down the railroad depot and destroyed some of its trestles, they turned their attention to an 800-foot railroad tunnel that had been cut through a mountain, north of the town.
Morgan's men set fire to a captured Union supply train, which Morgan had loaded up with hay, and pushed the train into the tunnel. Inside the tunnel, the wooden support beams caught fire and burned until they collapsed. This action would have the railroad and tunnel closed for months to come.
http://www.mycivilwar.com/battles/1862s.html
B+ Tuesday, August 12, 1862: C.S. General John Hunt Morgan’s cavalry captures US garrison at Gallatin, Tennessee. Morgan's men set fire to a captured Union supply train, which Morgan had loaded up with hay, and pushed the train into the 800 foot railroad tunnel. Inside the tunnel, the wooden support beams caught fire and burned until they collapsed. This action would have the railroad and tunnel closed for months to come. and destroys South Tunnel on the railroad.
https://sites.google.com/site/civilwarhardemancotn/departments/department-b/part-seventy
C Wednesday, August 12, 1863: Federal batteries on Morris Island open up a "ranging" barrage that will last four days.
http://blueandgraytrail.com/year/186308
C+ Wednesday, August 12, 1863: Siege of Charleston Harbor: Federal batteries on Morris Island start a ranging barrage, measuring the distance to various Confederate targets, that will last four days. ““They were only practice shots. They came from Parrott guns, which were named for their inventor and not tropical birds. These were special Parrott guns though, heavier in caliber than normal and rifled inside the barrel for greater accuracy and range [on the other side, the Confederacy got rifled cannon from Blakely in Britain…Barb]. The Federal forces had finally gotten them ashore on Morris Island in Charleston Harbor and installed them on their mountings in the sand. They fired off calibration shots today, intending only to test the aim of the weapons. They blew holes in the brick walls of Ft. Sumter with these test shots.”
https://bjdeming.com/2013/08/12/the-american-civil-war-150th-anniversary-august-12-18-1863/
D Friday, August 12, 1864: In Mobile Bay, the captured gunboat Tennessee, formerly of the Confederate navy, having had her smokestack replaced and other damage repaired, began her new career in the US Navy as she got up steam today. The Confederate raider, CSS Tallahassee, captures six more Federal vessels off the coast of New Jersey and New York, causing alarm up and down the eastern seaboard.
https://sites.google.com/site/civilwarhardemancotn/departments/1864/week-174
LTC Stephen C. CW5 (Join to see) CSM Charles Hayden SGM Steve Wettstein SFC William Swartz Jr SSG James J. Palmer IV aka "JP4" SSgt (Join to see) SSG Leo Bell SSG Ed Mikus SGT Randal Groover SGT (Join to see) SP5 Mark Kuzinski CPL Patrick Brewbaker SrA Christopher Wright PO1 John Miller SPC (Join to see) PO3 Steven Sherrill SN Greg Wright SSG Leonard J W. SGT Robert Hawks

The Union and Confederate Navies get my vote for today, LTC Stephen F.. I was unaware of the August 1861 Proclamation you found. Reading through the text, I couldn't help but think that such an action would also be appropriate in our own time. Thanks for the post.

Great share and read- thanks LTC Stephen F.