The assault mentioned was that on Fort Harrison on the fourth of September 1812. This post built by Harrison in his Tippecanoe campaign the year before, guarded the frontier farthest north and the river approach to Vincennes, some sixty miles below. At this time it was commanded by Captain Zachary Taylor (afterward President of the United States) and garrisoned by a small force so enfeebled by fever and ague that, by Taylor's account, there were not more than ten of fifteen able-bodied men. On the 4th the commandant had warning of the proximity of Indians and so, fortunately, was on his guard. Nevertheless one of about 600 warriors that quietly surrounded the fort that night, managed, under the cover of darkness, to drag himself to the walls of one of the buildings with a bundle of combustibles on his shoulders and the first intimation of the sentinels had of an attack was when the walls were ablaze. The barracks caught fire and not only the women and children, of whom there were nine, but the men themselves were thrown into panic and despair. Taylor's presence of mind saved the situation. He was that by throwing off the roof of the barracks building and saturating the walls with water the flames could be combated with promise of success, and when he ordered the men to this task they fell to with a will, led by Doctor Clark, the post surgeon, though a galling fire was directed upon them by the skulking savages from the woods. At this hazardous wok one man was killed and two wounded, but the blaze was subdued and a barricade of pickets put up across the gap in the stockade caused by the fire. Meanwhile the rest of the garrison, by the glare of the flames, were pouring their fire into such of the Indians as dared venture into the open, and thus managed to hold them off until daylight, when the besiegers withdrew, driving with them quantities of live stock (Taylor's official report).

Despite the seemingly overwhelming force of the assailants Taylor lost only three men, besides two or three wounded. At the beginning of the attack two men got over the stockade for the purpose of escaping but one was killed and the other one, wounded, returned to the gate and begged to be let in. He was obliged to lie there hidden until morning. The Indians who made the attack were supposed to have been Potawatomis, Kickapoos, Winnebagos and Miamis.

When word of the assault traveled to Vincennes troops were sent and the place reinforced but the Indians never returned.