In the Philippines, soon to be Major Richardson served as Assistant to the Assistant Chief of Staff for Operations, Headquarters, Philippine Department, Manila until April 6, 1923, when he returned to the United States to attend the Command and General Staff School at Fort Leavenworth, Kansas. Upon graduation in June 1924, Major Richardson sailed for France to attend the Ecole Superieure de Guerre, Paris, and upon graduation on September 2, 1926, he was ordered to Rome, Italy to serve as Military Attaché. In March 1928, newly promoted Lt. Colonel Richardson returned to the United States to join the 13th Cavalry at Fort Riley, Kansas.