On May 12, learning that Black Hawk's band was only twenty-five miles away, eager militiamen led by Major Isaiah Stillman left Whiteside's encampment, making another camp on a tributary of the Rock River later named Stillman Valley after him. Seeing a small party of natives with a red flag, Major Samuel Hackelton and some men pursued without waiting for orders, and Hackelton killed a native before returning to Whiteside's camp with the news. However, Black Hawk and others were nearby, and near dusk on May 14 attacked Stillman's party in what became known as the Battle of Stillman's Run. Accounts of the battle vary. Black Hawk later stated that he sent three men under a white flag to parley, but the Americans imprisoned them and opened fire on a second group of emissaries who followed. Some militiamen claimed they never saw a white flag; others believed that the flag was a ruse the Indians used to set an ambush. All accounts agree that Black Hawk's warriors attacked the militia camp at dusk, that the much more numerous militia were routed, and stragglers reached Whiteside's camp. To Black Hawk's surprise, his forty warriors killed twelve Illinois militiamen; his British Band suffered only three fatalities.