MGM, he wrote another play, See My Lawyer which was produced in New York by George Abbott and which starred Milton Berle. This was Maibaum's most successful play, running for 224 episodes from 1939 to 1940. MGM Maibaum's first credit was The Old School Tie (1936) at MGM. He did They Gave Him a Gun (1937) which he worked on with Cyril Hume. They worked on Live, Love and Learn (1937) and The Bad Man of Brimstone (1937) and Stablemates (1938) for Wallace Beery. Columbia At Columbia he wrote The Lady and the Mob (1938), Coast Guard (1939), The Amazing Mr. Williams (1939). Back at MGM he did The Ghost Comes Home (1940) and 20 Mule Team (1940) for Beery. He was one of many writers on Alfred Hitchcock's Foreign Correspondent (1940). Maibaum went to Paramount where he worked on I Wanted Wings (1941), a huge hit. He did some uncredited work on Hold Back the Dawn (1941). At 20th Century Fox he wrote Ten Gentlemen from West Point (1942). World War Two Maibaum joined the U.S. Army in 1942 and, like many other Hollywood writers and directors, was commissioned as a captain in the Signal Corps, During his four and one-half years in the army, he produced war morale films, assembled and disseminated combat film footage (presumably while stationed overseas) and supervised a documentary history of World War II, whose title, length, whereabouts, and, indeed, purpose, are currently unknown. He eventually achieved the rank of lieutenant colonel. He contributed to the story for the Olsen-Johnson film See My Lawyer (1945). Paramount With this experience under his belt, Maibaum returned to Hollywood for a contract at Paramount as a producer and screenwriter. He wrote and produced his first picture, O.S.S. (1946), which starred Alan Ladd in a fictional story of the newly formed Office of Strategic Services, the precursor to the CIA. This was the beginning of his fruitful association with Alan Ladd. Maibaum was producer on the John Farrow-directed The Big Clock (1948). He produced The Sainted Sisters (1948) with Veronica Lake, and Bride of Vengeance (1949) for director Mitchell Leisen. He wrote and produced The Great Gatsby (1949) also with Alan Ladd and co-written with Yale-educated Cyril Hume. John Farrow, original director of the project, quit after a casting dispute with Maibaum and was replaced by Elliott Nugent. Maibaum wrote and produced Song of Surrender (1949) for Leisen.