Battle of Ash Hollow The Battle of Ash Hollow , also known as the Battle of Blue Water Creek , was an engagement of the First Sioux War , fought on September 2 and 3 , 1855 between United States Army soldiers under Brigadier General William S . Harney and a band of the Brulé Lakota along the Platte River in present - day Garden County , Nebraska . The battle , which the American force won while killing Brulé women and children as well as warriors , was a punitive expedition for the so - called " Grattan Massacre " in August 1854 and for raids by Lakota in its wake during the year following . Overview . The battle was the defining engagement of a short war between the United States and the Sioux over disputes concerning violations of the Treaty of Fort Laramie . In this battle , 600 soldiers attacked 250 Sioux , killing 86 people . In March 1856 , without jurisdiction to do so , commanding General William Harney negotiated a peace treaty to stop further bloodshed with the Sioux and create a centralized tribal government among the Lakota by which leaders could be held accountable . While the battle was hailed by many newspapers as a heroic victory over the Indians , critics decried it as " " outright butchery " " . Some others claimed that the battle was fought only to justify growth in the American army , which was pushed for by then Secretary of War Jefferson Davis . Background . The events were catalyzed by a Mormon emigrant ' s losing a cow while traveling with his party on the Oregon Trail ; the animal wandered into a Brulé Lakota camp . A Sioux named High Forehead killed the cow for food . The Mormon farmer reported the cow as stolen to Army officers at Fort Laramie . The fort ' s commander sent out an inexperienced officer , Lieutenant John Lawrence Grattan , said to be contemptuous of the Indians , to arrest High Forehead , although such matters related to livestock and relations with settlers were supposed to be handled by the Indian Agent . Grattan vowed to take the wanted Indian " " at all hazards " " and took along thirty men and artillery . Grattan pressed the chief to surrender the Sioux man . One of his soldiers shot the chief Conquering Bear in the back and killed him . In the ensuing battle , the Sioux killed Grattan and twenty - nine of his men . One soldier survived the fighting but died later in the Fort Laramie hospital . President Franklin Pierce vowed to avenge the Grattan Massacre , as it was called by the press . The War Department appointed Harney in command with instructions to " " whip the Indians . " " In the ensuing debate , Grattan was blamed for the fracas in which he was killed . The expedition finally set out in August 1855 . On September 1 , 1855 , the expedition caught up with a Sioux encampment along the Platte River in a place known as Blue Waters . Harney sent a regiment in a long night flanking maneuver to set up a blocking position against which he would drive the Sioux . The flanking maneuver was led by Lieutenant Colonel Philip St . George Cooke and Captain Henry Heth . Harney moved up in the morning to drive the Sioux against Cooke and Heth . He first attempted to parlay with the Sioux chief , Little Thunder , but his demands to hand over the men responsible for the Grattan attack were rebuffed . The Sioux felt justified in having killed Grattan and his men as they had shot first . During the parlay , several Sioux braves discovered Cooke ' s men . Battle . Upon the Sioux discovery of Cooke ' s men , Harney opened the fight by attacking the Sioux camp . Some of the Sioux took refuge in caves along the river . Harney had his men fire into the caves , where they killed many women and children . A large group of mounted warriors made for an escape route away from Cooke ’ s and Harney ’ s forces , but Heth saw them and led his forces to block the escape route . The warriors managed to break through Heth ' s men , but were pursued on horseback by cavalry with Heth in the lead . They had a running fight for about five miles , which lasted several hours . At some point , Heth got so far ahead of his men that he was presumed killed in action . His death was reported in newspapers around the country , and he later took satisfaction in the obituaries his friends had written . The American forces were victorious and took prisoners . Among other American participants of the battle was Gouverneur K . Warren , who noted in his diary the horror of killing women and children . He later became a Union general during the American Civil War . Afterward , the army made a wide sweep of the surrounding Sioux country but encountered no further resistance . The Sioux called Harney " The Butcher " for the battle at Blue Water , " the Hornet " for invading their territory , and " the Big Chief Who Swears " for his handling of the treaty . Following this battle , there were about ten years of peace between the United States and the Sioux , who tried to ignore the many emigrants on the Oregon Trail .