Evarts began his military career by enlisting as a musician/drummer in Co. A, 2nd Virginia Infantry, Virginia National Guard in 1907 at the age of thirteen. Opie was commissioned a first lieutenant in 1911 and participated in the Mexican Border conflict in 1916. He accepted a regular Army commission in the cavalry in 1917 and remained with the United States Liquidation Commission in France following his service there during World War I.
He returned to the newspaper in 1920 as city editor of The Staunton Leader. He afterwards served as advertising manager, managing editor and general manager.
Evarts remained active in the Virginia National Guard in peacetime and assumed command of the 116th Infantry Regiment (the Stonewall Brigade) in October 1940 and was promoted to colonel. He led the regiment into Federal service on 3 Feb 1941 and expanded it to war strength and training for combat overseas at Fort George Meade, Maryland. In September 1941 he was promoted to Brigadier General and assigned as deputy commander of the Infantry Replacement Training Camp at Fort Walters, Texas. Following World War II, he returned to Staunton and again resumed his newspaper career. MG Opie retired as board chairman and editor of The Staunton Leader Papers in 1979.
Opie was active in many civic and church affairs and a lifelong member of Trinity Episcopal Church. He was chairman of the State Hospital Board, the Woodrow Wilson Birthplace Foundation and a past president and charter year member of the Staunton Rotary Club.
MG Opie died on 12 Mar 1982 in Staunton, Virginia. He rests forever in Thornrose Cemetery in Staunton, Virginia.
Evarts older brother, Hierome Lindsay Opie, was also a commander of the 116th Infantry Regiment and commanded the 3rd battalion of the regiment in WWI.