In the early years of the Great Depression, the Marine Workers Industrial Union (MWIU) was a colorful presence on the American Waterfront. In 1935, the MWIU seemed to vanish, closing its halls and stopping its publications. Vernon L. Pedersen convincingly demonstrates that the MWIU did not vanish—instead it was ordered by the Moscow-based Communist International to send its members into mainstream ALF unions and take over from the inside. Initiated by accident on the west coast and deliberately duplicated in the east, the Communists seized control of the west coast longshoremen’s union, destroyed the International Seamen’s Union, and created the Communist-dominated National Maritime Union.