In 1942, after completing Officer Training School and Army Air Force Intelligence school, Mark was assigned to a detachment which was to become part of the Allied Central Interpretation Unit in England, as a First Lieutenant. He was subsequently assigned to the Headquarters of the 12th Bomb Wing, which later became the Headquarters of the 4th Bomb Wing, and then the Headquarters of the 3rd Air Division. His assignment was as Chief Photo Interpreter.

The United States Air Force Academy hold the "Mark H. Brown Collection, 1929-1967" which contains extensive aerial reconnaissance photographs taken during World War II along with intelligence bomb plots and maps detailing those photographs. There are also numerous photographs taken throughout Europe depicting the devastation of the war. It details his experiences from 1942-1947. Official reports and records, printed matter, drawings, and artifacts are also contained within the collection.

See https://usafa.insigniails.com/Library/ItemDetail?l=All&i=551503&ti=0