What happened during the war of 1812?
Generally speaking, the war was a stalemate, with neither side really pushing advantages when they gained them, and both sides, especially the Americans, hamstrung by poor generalship. When the war opened, US forces seized control of the northern Great Lakes and the Northwest, but made the disastrous decision to invade Canada. The invasion resulted in the burning of the provincial capital of York by American forces (an act the British repaid with the burning of Washington D.C.) but the United States could not sustain control of Canadian soil. U.S. forces won several victories in the region, but generally failed to carry out a sustained campaign against the British.
Two major British offensives, one into New York, and another into the Chesapeake achieved little other than the aforementioned burning of the capital city. A third, a thrust against New Orleans, was repulsed by forces under General Andrew Jackson two weeks after the two nations had signed the Treaty of Ghent agreeing to end the war.
On the seas, the British were generally able to dominate the American navy, and blockaded American seaports, though American privateers were very effective in disrupting British shipping. Overall, the conflict was a stalemate, with British forces perhaps achieving the overall strategic upper hand. Except for crushing defeats inflicted on Indians in the Northwest, there were few decisive results to the war. But the young United States survived the conflict, and emerged from the war with an unprecedented, if short-lived sense of nationhood.