Blakeley attended Citizens' Military Training Camps during the expansion of the U.S. Army in anticipation of entry into World War I.

[3] In 1914, he competed for an appointment to the United States Military Academy from U.S. Representative Augustus P. Gardner and finished third on the competitive examination.

[4][5][a] With the army expanding for U.S. entry into World War I, in October 1917, Blakeley's application for a commission was approved, and he was appointed a second lieutenant of Field Artillery.

[4] In December 1917, he was transferred to the 4th Field Artillery Regiment, which performed security patrols on the Texas-Mexico border during the First World War.

[4][6] He was promoted to temporary first lieutenant in July 1918 and in August he was assigned to the 1st Field Artillery Regiment at Fort Sill, Oklahoma.

[1] In December 1918 he was appointed aide-de-camp to Brigadier General Laurin Leonard Lawson, commander of the 15th Field Artillery Brigade at Camp Stanley, Texas.

[7] During 1919 and 1920, he toured First World War battlefields and was assigned as a courier between several European countries, including France, Belgium, Holland, Switzerland, Czechoslovakia, Austria, and Poland.

[12] In 1934, Blakeley was the army's technical advisor on the film Keep 'Em Rolling, the plot of which revolves around a World War I Field Artillery horse and soldier.

[13] In January 1935, Blakeley was selected to attend the United States Army Command and General Staff College, and he was promoted to major in August 1935.

[25] In the summer of 1945, the 4th Infantry Division returned to the United States to reorganize for combat in the Pacific theater, but the surrender of Japan in September ended the requirement.

[27] In addition, his foreign awards included the French Legion of Honor (Chevalier) and Croix de Guerre with palm.

He proceeded along the shell-swept road at great personal risk ... By his courageous action ... he was materially responsible for the success of the operations.