Throughout 1915–16, the Interior Department was organizing itself to deal with the growing number of national parks and ultimately, Congress created the National Park Service on August 25, 1916. Prior to the establishment of the National Park Service, in July 1916 the War Department agreed to withdraw troops from Yellowstone as of October 1, 1916, which was the end of the park visitation season. At the same time, the War Department agreed to discharge a select number of the current volunteer cavalry contingent on September 29, 1916, so they could go to work for the National Park Service as Park Rangers.