On the first of August the Indians reached the Mississippi and began crossing in two canoes. In the afternoon the steamer Warrior, which had been sent up from Fort Crawford to notify the Sioux Chief, Wabasha, one hundred and twenty miles above to look out for his enemy, Black Hawk, who was headed that way, stopped opposite the spot where the Indians had gathered. Black Hawk raised a white flag and tried to parley; but the captain assumed that it was an attempt to trap him and, without warning, fired into the Indians at short range with a cannon loaded with cannister. Thus a second time was the usage of all nations violated in this war by refusing to recognize the flag of truce. Twenty-three were killed by this discharge. There were twenty riflemen on the boat who then began firing, and the Sauks responded. The Warrior soon after steamed away to Fort Crawford, twenty miles below, and the Indians continued their efforts to cross the river, here three hundred rods wide and running a strong current. Some were drowned and others were carried down the stream on improvised rafts. A few of these were rescued at Prairie du Chien.
The next day Atkinson appeared on the ground. Black Hawk seems to have been utterly demoralized and had told those who had not crossed that he was going to the Chippewa country, and that they had better follow. Only a few did so, and after going a few miles he turned back on August 2nd, just in time to see the closing scene of the massacre called the battle of Bad Axe.
As Atkinson approached he was skilfully decoyed beyond the Indian camp some distance, but its location was finally discovered and a fierce onslaught was made. The poor wretches at first begged for quarter, but as the soldiers shot them down without discrimination, they fought for a time with desperation, and then men, women and children plunged into the river, the most of them to drown before reaching the other side. The steamer Warrior reappeared, and the sharpshooters fired at the swimmers, some of them women with babies on their backs. The incidents of the merciless slaughter are too harrowing for recital, and would be incredible if not thoroughly authenticated. It is difficult to understand the ferocity with which Black Hawk's band was pursued and destroyed. Probably the belief that he was still in the British service had much to do with it; also his first success at Stillman's Run, and the murder of the whites in Northern Illinois by marauders from other tribes, which were unjustly charged to him, may account for it in large part. About three hundred Indians succeeded in crossing the river, but their ill fate still pursued them. Their fierce enemy, Wabasha, was on their track, and before reaching the Iowa river half of the three hundred had been relentlessly slain. Of the twelve hundred who crossed the Mississippi in April, only one hundred and fifty, and they barely living skeletons, returned in August.