mines, but, critically to the future success of the invasion, Clark reported that the North Koreans had not in fact systematically mined the channels. When the KPA discovered that the agents had landed on the islands near Incheon, they made multiple attacks, including an attempted raid on Yonghung-do with six junks. Clark mounted a machine gun on a sampan and sank the attacking junks. In response, the KPA killed perhaps as many as 50 civilians for helping Clark. Bombardments of Wolmido and Incheon On 10 September 1950, five days before the Incheon landing, 43 American warplanes flew over Wolmido, dropping 93 napalm canisters to "burn out" its eastern slope in an attempt to clear the way for American troops. The flotilla of ships that landed and supported the amphibious force during the battle was commanded by Vice Admiral Arthur D. Struble, an expert in amphibious warfare. Struble had participated in amphibious operations in World War II, including the Normandy landings and the Battle of Leyte. He got underway for Incheon in his flagship, the heavy cruiser , on 12 September 1950. Among his ships were the Gunfire Support Group, consisting of Rochester, the heavy cruiser , the British light cruisers and , and the six US destroyers of Task Element 90.62, made up of , , , , , and . Royal Canadian Navy destroyers , and also participated in the invasion task force. At 07:00 on 13 September, the U.S. Navy's Destroyer Squadron 9, headed by Mansfield, steamed up Flying Fish Channel and into Incheon Harbor, where it fired upon KPA gun emplacements on Wolmido and in Incheon. Between them, two British cruisers and six American destroyers fired almost a thousand 5-inch (127-mm) and 6-inch (152-mm) shells onto the fortifications. The attacks tipped off the KPA that a landing might be imminent, and the KPA officer in command on Wolmido assured his superiors that he would throw their enemies back into the sea. North Korea's 918th Coastal Artillery Regiment returned fire, hitting Collett seven times, Gurke three times, and Lyman K. Swenson twice. Aboard Lyman K. Swenson, Lieutenant (junior grade) David H. Swenson was killed and eight others were wounded. The American destroyers withdrew after bombarding Wolmido for an hour and Rochester, Toledo, Jamaica, and Kenya proceeded to bombard the KPA batteries for the next three hours from the south of the island. Lieutenant Clark and his South Korean