that I-10 would arrive at Truk via the North Channel on 10 February 1944, but she arrived safely at Truk on 10 February despite the Allied knowledge of her schedule. Operation Hailstone During I-10′s stay at Truk, U.S. Navy Task Force 58 conducted Operation Hailstone, a major attack on Truk by carrier aircraft supported by anti-shipping sweeps around the atoll by surface warships, on 17 and 18 February 1944. I-10 suffered three killed and two wounded and sustained minor damage during the first day of the raid, but she and the submarines and put to sea on 17 February in an attempt to intercept the attacking ships. I-10 searched for them east of Dublon (known to the Japanese as Natsushima) without success and returned to Truk. Sixth war patrol I-10 departed Truk for her sixth war patrol on 25 February 1944, intending to operate off the U.S. West Coast. On 4 March 1944, however, she suffered damage in a depth-charge attack in the Pacific Ocean east of Mili Atoll and was forced to abort her patrol. She arrived at Yokosuka on 20 March 1944 for repairs. While she was under repair, workers probably installed an E27 Type 3 radar detector and a Type 3 sonar aboard her. Seventh war patrol With her repairs complete, I-10 left Yokosuka on 4 May 1944 with a Yokosuka E14Y1 (Allied reporting name "Glen") floatplane embarked to begin her seventh war patrol, assigned a patrol area in the Pacific Ocean east of the Marshall Islands. After dark on 12 June 1944, her floatplane reconnoitered the American fleet anchorage at Majuro Atoll, but an American expeditionary force had departed Majuro six days earlier, and the plane's crew found no ships there. Upon returning to I-10, the floatplane capsized and was lost, although I-10 recovered its crew. On 13 June 1944, the commander-in-chief of the Combined Fleet, Admiral Soemu Toyoda, activated Operation A-Go for the defense of the Mariana Islands and ordered the commander-in-chief of the 6th Fleet, Vice Admiral Takeo Takagi on Saipan, to redeploy all 6th Fleet submarines to the Marianas. Takagi, in turn, ordered all 18 available submarines, including , to deploy east of the Marianas. The Marianas campaign began on 15 June 1944 with U.S. landings on Saipan, beginning the Battle of Saipan and disrupting communications with Takagi, so the commander of Submarine Squadron 7, Rear Admiral Noboru Owada, took temporary command of