In 1920, William S. Key, having attained the rank of Lieutenant Colonel, was discharged from the US Army after World War I to resume his commission in the Guard. He was appointed Captain, Field Artillery, Oklahoma Army National Guard and assigned to organize a tight artillery battery at Wewoka, Oklahoma. This horse drawn 75mm battery was federally recognized as Battery A, 1st Oklahoma Field Artillery on July 28, 1920. As white horses served as artillery animals, Battery "A" became known as the "White Horse Battery". Other artillery elements were organized in the Oklahoma National Guard, and on 18 July 1921, the 1st Oklahoma Field Artillery Regiment, consisting of a Regimental Headquarters and two firing battalions was federally recognized. In October 1921, the 1st Oklahoma Field Artillery became the 160th Field Artillery Regiment, consisting of the 1st and 2nd Battalions.