[1] During the Spanish–American War, Johnson served as a first lieutenant with the 17th Infantry Regiment, which participated in the siege and surrender of Santiago, Cuba.

Following his service in the Philippines, he instructed and inspected the Minnesota Militia until September 2, 1913, when he was transferred to Texas where he commanded a battalion of the 22nd Infantry Regiment until December 1914.

[7] Promoted to colonel on May 15, 1917, Johnson commanded the 36th Infantry Regiment at Fort Snelling, Minnesota from June to July 1917.

During his command, he received the Army Distinguished Service Medal and the Legion of Honour for efficiently utilizing female labor in Nevers, France.

[1] The citation for his Army DSM reads: The President of the United States of America, authorized by Act of Congress, July 9, 1918, takes pleasure in presenting the Army Distinguished Service Medal to Brigadier General Arthur Johnson, United States Army, for exceptionally meritorious and distinguished services to the Government of the United States, in a duty of great responsibility during World War I.