Motor Torpedo Boat PT - 346 USS " PT - 346 " was an 80 ft Electric Launch Company ( Elco ) Motor Torpedo ( PT ) Boat which suffered the worst PT - boat friendly fire casualties of World War II , with nine men killed and nine wounded . The incident . The majority of all friendly fire PT boat casualties during World War II occurred in the Southwest Pacific in two separate incidents occurring over the span of one month - the first on 27 March 1944 , and the second on 29 April 1944 . " PT - 346 " , skippered by Lieutenant James Burk , USNR , was the rescue vessel in March and the victim in April . PT boat Squadron 25 took the brunt of both incidents , which resulted in 22 men killed , including Burk , and 28 wounded . On March 27 , 1944 , " PT - 346 " and " PT - 354 " rescued the survivors of " PT - 353 " and " PT 121 " , which had been mistakenly destroyed during a mission off the coast of New Britain by five fighter planes under the command of the Royal Australian Air Force . Just over a month later , " PT - 346 " itself became the victim of friendly fire . The morning of April 29 , 1944 , " PT - 346 " was send to the aid of " PT - 347 " , commanded by Lieutenant Robert J . Williams , USNR , and " PT - 350 " , skippered by Stanley L . Manning , USNR . " PT - 347 " had become stuck on a reef during a night patrol to intercept enemy barges and destroy shore installations off the coast of Rabaul in Lassul Bay , located off the northwest corner of New Britain Island in New Guinea . ( The waters of the Pacific were not well charted and during World War II , more PT boats were lost to reefs than to enemy fire . ) At 0700 , " PT - 350 " was attempting to dislodge " PT - 347 " from the reef , when two American Marine Corsair planes mistook the PT boats for Japan ese gunboats and attacked . Taking heavy fire from the planes , " PT - 350 " shot down one of the two attacking fighter s , believing them to be A6M Zero s . With three dead and four wounded and serious mechanical problems , " PT - 350 " headed back to base . " PT - 347 " remained stuck on the reef . Lieutenant Burk headed out with his crew and the base commander of the 25th Squadron , Lieutenant James R . Thompson , USNR , and Chief Pharmacist First Class John Frkovich , USNR , to render medical aid . When " PT - 350 " could not be boarded because of extensive damage , " PT - 346 " headed out to " PT - 347 " to provide assistance . " PT - 346 " arrived at 1230 , and at 1400 was still attempting to dislodge " PT - 347 " from the corral heads when planes appeared . The Corsair plane from the morning run brought back an entire squadron of 21 planes ( four Corsairs , six TBF Avenger torpedo bomber s , four F6F Hellcat fighters , and eight SBD Dauntless dive bomber s ) . Recognizing the planes as American and thinking they were the air cover he had ordered , the squadron commander ordered the men to keep working ; however , the planes attacked the two boats , still mistaking them for Japanese gunboats . " PT - 346 " did not respond defensively until it was too late , and took heavy casualties . The skipper of " PT - 347 " , Lieutenant Williams , who had experienced the earlier attack , ordered his men into the water and to stay dispersed , but two men were killed and three wounded . " PT - 346 " and " PT - 347 " were completely destroyed by bombs , and the men were strafed in the water for approximately one hour , continuing to dive under the water to survive as the planes approached . Heroes of the day included Wilbur Larsen , USNR , motor machinist ’ s mate third class of " PT - 347 " , who received the Navy Marine Corps medal for saving wounded non - swimmer Forrest May ’ s life , and Lieutenant James Burk , who received the Purple Heart . Mortally wounded , Burk ordered medic John Frkovich to take his life jacket so he could survive and treat the wounded . Causes and inquiry . Factors that contributed to the incident included an influx of new pilots who lacked experience in recognizing PT boats , poor communications between the planes and PT boats , and the fact that the incident occurred in an area of the Pacific which was the " line of demarcation " between Nimitz and MacArthur ’ s Pacific commands , which meant that coordination of reports between the two commands did not always occur . A formal inquiry into the incident was conducted and improvements instituted as a result of the tragedy . United Press . “ U . S . Planes Sink 3 U . S . PT Boats ; 2 Shot Down in Mix - up of Signals . ” New York Times , page 1 .