On June 18, 1812, the War of 1812 began as the United States declared war on Britain. An excerpt from the article:
"When James Madison was elected to the presidency in 1808, he instructed Congress to prepare for war with Britain. On June 18, 1812, buoyed by the arrival of "war hawk" representatives, the United States formally declared war for the first time in the nation's history. Citizens in the Northeast opposed the idea, but many others were enthusiastic about the nation's "Second War of Independence" from British oppression.
Ironically, the British Parliament was already planning to repeal its trade restrictions. By the time the ship carrying news of the declaration of war reached Great Britain, almost a month and a half after war had been declared, the restrictions had been repealed. The British, however, after hearing of the declaration, chose to wait and see how the Americans would react to the repeal. The Americans, after hearing of the repeal, were still unsure how Great Britain would react to the declaration of war. Thus, although one of the main causes for war had vanished, fighting began anyway.
The poorly trained U.S. army, numbering roughly 6,700 men, now faced an experienced adversary fielding over 240,000 soldiers spread across the globe. America's military fleet was large, but Britain's was much larger."