The Siege of Fort Wayne took place between American and Indian forces in the wake of the successful British campaigns of 1812.
Since 1811, after the severe defeat at the Battle of Tippecanoe, Native American tribes on the Northwest frontier had been growing more and more bitter at the U.S. presence there. Encouraged by other British/Native American victories at places such as Fort Dearborn and Detroit, native tribes began to undertake campaigns against other smaller American outposts.
In September 1812 Indians from the Potawatomi and Miami tribes, led by Chief Winimac, undertook a campaign against Fort Wayne in northeast Indiana Territory. Captain James Rhea commanded the garrison at Fort Wayne. Rhea began to worry about his position once Fort Dearborn and Detroit fell. The growing Indian threat outside the fort led Rhea to begin drinking heavily. Once several occasions Rhea invited Indian delegates into the fort to discuss terms of peace with the Indians (mostly to ensure his own personal safety).
On September 5, the siege began when Chief Winimac assaulted the fort from the east side and burned the homes of the surrounding village. The Indians also constructed 2 wooden cannon and were able to trick the garrison into thinking they had artillery besieging the fort as well. When Rhea began to discuss ideas of surrender, 2 of his lieutenants decided he was unfit to continue his duties and relieved him of command. These 2 lieutenants then assumed command and continued to hold out in the fort until reinforcements arrived.
Gen. William H. Harrison, the newly appointed commander of the Northwest frontier, personally led a relief force of 2,200 soldiers to Fort Wayne, arriving there on September 12. Harrison attacked and defeated the Indian force, lifting the siege. The Potawatami/Miami force retreated into Ohio and Michigan Territory. Harrison had originally arrested Rhea but allowed him to resign instead, he then placed Lt. Philip Ostander (1 of the 2 lieutenants that had relieved Rhea) in command of the fort.
The siege prompted Harrison to order punitive expeditions against the Miami which culminated in the Battle of the Mississinewa. The defeats at the Battle of Fort Harrison and the Siege of Fort Wayne caused the Miami warriors to lose confidence in their chiefs. Many of them turned instead to the influential leadership of Tecumseh and joined his Confederacy. No further Indian attacks occurred in the Indiana Territory for the rest of the war, but it was not until Tecumseh's defeat at the Battle of the Thames that the Indian threat was really eliminated.