a Sikorsky R-6A from an Aircraft Repair Unit in 1945, part of Operation Ivory Soap, the WWII experiment that created modern helicopter combat missions

Between June 15 and July 29, 1945, six Army Air Forces pilots flying experimental Sikorsky helicopters evacuated between 75 and 94 wounded American soldiers from the Philippine jungles while under Japanese fire. Their mission was to transport aircraft parts, not casualties, but the pilots felt differently.

Those six weeks of improvised rescues became the first combat helicopter medical evacuations under hostile fire in military history. While the numbers were small compared to later conflicts, it proved that helicopters could save lives on the battlefield - a concept that would reshape military aviation and lead directly to Army MEDEVAC and Air Force Pararescue units today.

As American forces island-hopped across the Pacific in late 1943, damaged aircraft were piling up at forward airstrips without adequate repair facilities. European bases had established infrastructure with machine shops and trained mechanics. Pacific airfields usually didn't.

Gen. Henry "Hap" Arnold, commanding the Army Air Forces, authorized a classified program to convert six Liberty ships into floating maintenance depots, each carrying 344 personnel. Eighteen smaller auxiliary vessels with 48-person crews would handle fighter aircraft maintenance. The ships would be stocked with machine shops, specialized tools, and massive inventories of replacement parts for B-29 bombers and P-51 Mustangs.

According to Lt. Col. Matthew Thompson, who led the training effort, the program got its code name when someone suggested "Ivory Soap" during a planning meeting - both the soap and the repair ships would float.

Thompson had to train 5,000 airmen to become sailors in less than five months. Ed Roberts, owner of the Grand Hotel in Point Clear, Alabama, donated his resort to the military. Training began July 10, 1944. The hotel became a maritime school where trainees called floors "decks," kept time by a ship's bell, and followed Navy protocols for smoking.

By October 1944, the first converted Liberty ship departed Mobile. All six reached the Pacific by February 1945, supporting operations at Iwo Jima, Okinawa, and the Philippines. Unlike most other ships of the time, each repair ship featured a 40-by-72-foot steel platform for helicopter operations.

https://www.military.com/feature/2025/10/21/operation-ivory-soap-wwii-experiment-created-modern-helicopter-combat-missions.html