In June 1962, Forsythe became executive officer and senior aide to the Chief of Staff of the United States Army, both General George H. Decker and General Earle G. Wheeler.

In 1967/8 Forsythe served as military deputy to Robert Komer the head of Civil Operations and Revolutionary Development Support.

[1] Forsythe served as commander of the 1st Cavalry Division from August 1968 until April 1969.

[2] In May 1969 Forsythe was appointed commandant of the United States Army Infantry School.

[3] Project VOLAR was launched on January 1, 1971, to determine how to successfully transition the Army to an all volunteer organization.