sink retreating Japanese ships, to provide lifeguard services, and to guard the major passages from the Java Sea (the Sunda Strait and Lombok Strait) to the Indian Ocean lest the Japanese try to move into the Indian Ocean to attack the Allied strike force. Launched as scheduled on 17 May the strikes achieved complete surprise. The only action of the patrol for Angler came on 20 May, when she torpedoed and sank Otori Maru. Japanese escort vessels administered a bad pounding to Angler, but she escaped damage. The next day, nausea again gripped everyone on board Angler. The situation was reported to Fremantle, and the submarine was ordered to return at once. Things onboard Angler continued to grow worse. On 22 May, Lieutenant Commander Olsen noted in the log: "Physical condition of officers and crew is so bad that it is difficult to maintain watch, either surface or submerged. Put crew on fruit juice alone, no water. Held thorough field day in case boat is contaminated. Exercised special supervision in cooking, dishwashing." On 23 May he wrote, "Decided to run submerged as we did not have enough able-bodied people to maintain proper surface watch." and were sent to intercept Angler and lend assistance. also arrived and transferred a doctor to assist the ailing crewmembers. Angler finally arrived at Fremantle on 29 May. An investigation concluded that an electrician had taken a can of carbon tetrachloride on board as a cleaning agent, which was strictly forbidden. Although the illness was attributed the tetrachloride, some suspected that the fresh water tanks had not been cleaned as requested. Angler began her fourth war patrol on 21 June. She paused to refuel alongside a barge in Exmouth Gulf on 24 June, and while maneuvering into position, hit an uncharted obstruction. Returning to Fremantle for repairs, Angler was underway again on 29 June with a new starboard propeller. She rendezvoused with Flasher and Crevalle to carry out one of the first "wolfpack" patrols of the war. The group worked the middle area of the South China Sea and along the Indochinese coast, without success. They were then ordered to move to a position off the west coast of Luzon. On 25 July, Angler and her sister ships picked up a large northbound convoy and began a series of attacks over the next few days. While Angler failed to damage any ships, the pack as a