The Lee W. Mayo Collection includes information of Lee while being enlisted in the US Army in October of 1941, just before Pearl Harbor Day. He kept a diary, titled "My Life in the Service" between July 23, 1944 and December 18, 1945, while moving around the South Pacific. He spent most of that time in the Philippines, fighting in the Battle of Manila in 1945, but also visited and wrote about other locations on Luzon and Leyte.

Mayo starts by listing several of his "Buddies in the Service," and goes on to write about such things as Japanese suicide bombers attacking his ship, Japanese soldiers committing suicide to avoid being captured, civilian populations on some of the islands they stop on, bartering and attending boxing matches with Australian soldiers, personal illnesses including "jungle rot" and "yellow jaundice," his fellow soldiers, K-rations, and the weather. The diary also includes loose and pasted-in ephemera, his "Soldier's Individual Pay Record," and immunization records, with the ending pages filled with pasted-in photographs of a woman and children, many posed in front of a house.