Arthur MacLennan was born in Philo, Illinois, on December 24, 1886. Around 1907, MacLennan left the University of Illinois for a career in the newspaper industry; he worked for publications in the United States, Mexico, China, and elsewhere in Asia, including the Denver Times, China Press , and San Francisco Examiner. In 1917, MacLennan attended the Reserve Officers' Training Camp at the Presidio in San Francisco, California; after being placed in a cavalry regiment, he requested a transfer to the intelligence department. In October 1918, he served in the 301st Cavalry at Camp Kearny, California, and in the 46th Field Artillery at Fort Sill, Oklahoma, where he was a first lieutenant. Arthur MacLennan died on February 5, 1941.