Firsts

In the first battle of the War of 1812 on American soil — at Brownstown, August 5, 1812 — the only British troops in actual combat were Indians, under Tecumseh. The first United States soldier to be killed in the War of 1812 was Captain McCullough, killed in this battle of Brownstown, and he was scalped by an Indian before he was dead. The first victory of the British in the War of 1812 was the capture of Mackinac, and it is well to remember that the government of the United States took -especial pains to inform the British commanders of the declaration of war a week or ten days 

before it informed the commanders of our own forts and troops, and as a result the commander of the fort at Mackinac did not know of the declaration of war until he was summoned to surrender although that was more than a week after that declaration was known to the British forces that summoned him to surrender. [Source]