Mezue ahịrịokwu na-esonụ: E nyere McRae ọrụ na ndị agha nke atọ ma rụọ ọrụ ókèala site na 1886-1888. N'oge Spanish-American War, ọ nọ na
Agha nke El Caney na Cuba, ọ rụkwara ọrụ na Sanitary Corps, nke ọ natara Silver Star Commendation mbụ ya. O nwetara Silver Star nke abụọ ya n'oge Philippine Insurrection ma kwado ya maka nkwalite brevet. Site na 1905 ruo 1908, o jere ozi na General Staff, na 1911, ọ gụsịrị akwụkwọ na United States Army War College. McRae jere ozi na Ngalaba Adjutant General site na 1913 ruo 1917, na August 5, 1917, e buliri ya n'ọkwa brigadier general ma nye iwu na 158th Depot Brigade na Camp Sherman, Ohio. Na mgbakwunye, o duziri Ninth Infantry Brigade nke Fifth Infantry Division. E buliri ya n'ọkwa onye isi ndị agha na Eprel 12, 1918, ma nye iwu nke 78th Infantry Division (AEF) ruo June 1919, mgbe a kwụsịrị ya. N'ihi nke a, e nyere ya ihe nrite maka ọrụ dị iche iche ọ rụrụ. N'afọ 1921 na 1922, ọ bụ osote onye isi, G-1 (ndị ọrụ).