Operation Drumbeal The state's vulnerability became evident shortly after Pearl Harbor. In early 1942 German submarines opened an offensive, code named Operation Drumbeat, against the virtually undefended Allied shipping lanes along the East Coast. Before the carnage was over, nearly 400 ships had been sunk, and thousands of lives lost. Dozens of ships were torpedoed just off Florida's Atlantic coast and others in the Gulf of Mexico, German submarine skippers used the light of coastal cities to silhouette their targets. Oil, debris, and dead bodies washed up on the beaches, mixing with the driftwood and seashells along Florida's Atlantic coast. What is the main idea of this passage? Pearl Harbor was one of the worst attacks on American soil in history. Germany used submarines to sink ships that sailed from America's East Coast. The United States had one of the strongest shipping fleets in the world in the 1940s. The United States used Operation Drumbeat to defeat German submarines.