On May 17, 1756, Britain declared war on France (7 Years' War or the French and Indian War). From the article:
"Seven Years’ War
The Seven Years’ War (1756-1763) was a global conflict that spanned five continents, though it was known in America as the “French and Indian War.” After years of skirmishes between England and France in North America, England officially declared war on France in 1756, setting off what Winston Churchill later called “the first world war.” While the French, British, and Spanish battled over colonies in the New World, Frederick the Great of Prussia faced off against Austria, France, Russia and Sweden. The Seven Year’s War ended with two treaties. The Treaty of Hubertusburg granted Silesia to Prussia and enhanced Frederick the Great’s Power. The Treaty of Paris between France, Spain and Great Britain drew colonial lines largely in favor of the British, an outcome that would later influence the French to intervene in the war for American Independence.
The French and Indian War
By the 1750s, the French had largely claimed Canada and the Great Lakes, while Great Britain clung to their 13 colonies on the Eastern seaboard. The frontier area around the upper Ohio River Valley soon became a hotbed of contention between British, French and Native American forces, with the Europeans eager to settle the area over their rivals. The initial armed conflicts did not go well for England; the French built Fort Duquesne and alongside their Native American allies, repeatedly defeated the British.
The war was officially sparked when 22-year-old George Washington was sent by the governor of Virginia as an envoy to the French, warning them to stay away from the area around today’s Pittsburgh. The French refused, and on the way home from his failed mission, Washington’s men became embroiled in a skirmish with a French encampment, where French ensign Joseph Coulon de Jumonville was killed. Rightly fearing reprisal, Washington ordered the construction of the aptly-named Fort Necessity. The Battle of Fort Necessity on July 3, 1754, (also known as the Battle of Great Meadows) resulted in General Washington’s first, and only surrender... and global war.
Washington would soon be followed in defeat by General Edward Braddock and Governor William Shirley of Massachusetts, both of whom failed to stop the French. In 1756, British Prime Minister William Pitt decided to take a new tack and began strategically financing Prussia’s army as it took on France and its allies. Pitt also reimbursed the colonies for raising armies to beat back the French in North America.
British Victory in the French and Indian War
Pitt’s gambit worked. The first British victory at Louisburg in July of 1758 revived the sagging spirits of the army. They soon took Fort Frontenac from the French and in September of 1758, General John Forbes captured Fort Duquesne and rebuilt a British fort called Fort Pitt in its place in honor of William Pitt. From there, British forces marched to Quebec, beating French forces in the Battle of Quebec (also known as the Battle of the Plains of Abraham) in September 1759. Montreal fell in September of the following year.
The British under George III were not just fighting over territory in the Americas; they were simultaneously involved in maritime battles that tested the might of the British Navy. The French had to scrap an attempted invasion of Britain after losing the Battle of Lagos and the Battle of Quiberon Bay in 1759. In addition to the victories in Canada, Great Britain beat back French forces in Guadeloupe, Martinique, Havana, Manila, West Africa and India, wresting Pondicherry from the French on January 16, 1761.
The Treaty of Paris
The Treaty of Paris was signed on February 10, 1763, officially bringing an end to the French and Indian War. The British were awarded Canada, Louisiana and Florida (the latter from Spain), thereby removing European rivals and opening up North America for Westward expansion.
The Treaty of Paris also returned Pondicherry to France, and gave them back valuable colonies in the West Indies and Senegal. The British victory in the French and Indian War earned England a reputation as a world power with a strong navy, a reputation they would use to continue their empire-building around the globe. The French loss would later inspire them to side with American patriots against the British during the Revolutionary War.
The Seven Years’ War in Europe
The Seven Years’ War picked up where the War of the Austrian Succession left off in 1748: with increasing levels of hostility between Prussia, led by Frederick the Great, and Russia. The Treaty of Aix-La-Chapelle, or Treaty of Aachen, had taken Silesia from Austria and given it to Prussia, prompting Russia to worry about Frederick’s growing influence in the region. Frederick, for his part, welcomed another war where he could gain even more territory. With tensions mounting between the superpowers, Europe’s system of alliances shifted in what came to be known as the “diplomatic revolution”: Russia soon allied itself with France and Austria against Britain, Prussia and Saxony.
Frederick made the first move, kicking off the war in Europe when he invaded Saxony in August 1756, quickly taking Leipzig and Dresden before moving on to attack Bohemia. Following a failed siege of Prague in May of 1757, he earned early victories at Rossbach on November 5, 1757, when Prussian forces defeated France and Austria, and again at the Battle of Leuthen on December 5, 1757, when the Prussians were victorious over the Austrians. It was at Leuthen that Frederick began to rely less heavily on swordsmanship and more on firepower to keep up with the advanced weaponry of his opponents.
Prussia’s enemies would soon strike back: Russian and Austrian forces occupied Berlin, which was then the Prussian capital, in October of 1760. The Russians and Austrians withdrew as Prussian reinforcements arrived to battle for their capital.
Prussia was winning, but at great cost. It would take a miracle—the “Miracle of the House of Brandenburg”—to end the war. That miracle happened when Russia withdrew from the war in 1762 following the death of its leader, Tsarina Elizabeth, and the ascension of her nephew, Czar Peter III, to the throne.
The Treaty of Hubertusburg
The Treaty of Hubertusburg (also known as the Peace of Hubertusburg) between Austria, Prussia, and Saxony was signed five days after the Treaty of Paris on February 15, 1763. It named Archduke Joseph of Austria Holy Roman Emperor and gave Silesia and Glatz to Prussia, further bolstering the power and influence of Frederick the Great and Prussia."