As a captain, Johnson helped co-author the regulations implementing the Selective Service Act of 1917. Without Congressional authorization, he ordered completed several of the initial first steps needed to implement the draft. The action could have led to his court-martial had Congress not acted (a month later) to pass the conscription law. He was promoted to colonel on January 8, 1918, and to brigadier general on April 15, 1918. At the time of his promotion, he was the youngest person, at the age of 35, to reach the rank of brigadier general since the Civil War, and the youngest West Point graduate to remain continuously in the service who had ever reached the rank. Ohl (1985) finds that Johnson was an excellent second-in-command during the war in the Office of the Provost Marshal under Brigadier General Enoch H. Crowder as long as he was closely watched and tightly supervised. His considerable talents were effectively drawn upon in the planning and implementation of the registration and draft before and during the conflict. However he was never able to work smoothly with others.