On July 11, 1886, after a leave of absence of two months, Forsyth was promoted to Colonel of the 7th U.S. Cavalry, assumed command of the regiment July 26, 1886, at Fort Meade, South Dakota and marched to Fort Riley, Kansas, where he arrived September 8, 1887, where he remained in command until Nov. 10th, 1890, during which time he organized and developed the system of instruction for light artillery and cavalry for the School of Application for Infantry and Cavalry. Forsyth was in command of the 7th Cavalry at the Wounded Knee Massacre on December 29, 1890 and at the Drexel Mission Fight that took place on the Pine Ridge Indian Reservation on December 30, 1890.