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.