Ian Rocksborough-Smith interviewed William D. Riddell about his new book On the Waves of Empire: U.S. Imperialism and Merchant Sailors, 1872-1924, published by the University of Illinois Press in 2023. Set mainly in the years preceding and following the Spanish-American War (1898) through World War I (1914-1918) and its aftermath, the book looks especially at the experiences of merchant sailors, their unions, and their labor leaders to indicate how class conflict impacted America’s emergent 20^th Century empire.