There are countless examples of battles that take place in wars after a peace treaty is signed. The last battle of the Civil War was a skirmish in Texas that Confederate forces won, nearly a month after Lee's surrender at Appomattox. As fate would have it, the last fighting of the Civil War took place two days after Confederate President Jefferson Davis had been captured in Georgia

It's certainly rare for the most famous battle of a war to take place after the peace treaty is signed, but luckily for Andrew Jackson, the War of 1812 was that unique exception. Less than a year after his victory in the Battle of Horseshoe Creek, Jackson led his forces into a more important battle at the Battle of New Orleans. The British hoped to grab as much of the land on the western frontier as they could, especially New Orleans, which had a prominent position on the Mississippi River for trading. With more than 8,000 soldiers aboard a British fleet sailing in from Jamaica in early January 1815, the attack on New Orleans promised to be a significant one, while Jackson's men defended New Orleans with about half that number. This went on despite the fact that the two sides had signed the Treaty of Ghent on Christmas Eve 1814, which was supposed to end the war. 

Despite the fact the French & Indian War had recently concluded, Pontiac led the first major attack of Pontiac's War in May 1763, when he and 300 of his men attacked Fort Detroit in what is now the city by the same name. Unfortunately for his cause, Pontiac failed to gauge just how strong the British presence there was, and his attack was quickly repelled. On the other hand, he was not a man who gave up easily, so instead of retreating, he and his warriors would lay siege to the British stronghold. In the days that followed, word spread of his efforts, and in short order nearly 1,000 men from various tribes in the area had joined him.