In February 1942, Colonel Percy J. Carroll, the Chief Surgeon of the US Army Forces, Southwest Pacific Area, found that he had problems integrating large 400 to 750-bed field and evacuation hospitals into troop flow as forces advanced because of the underdeveloped transportation infrastructure and terrain in the Southwest Pacific, particularly in Papua and New Guinea. This limited his ability to move hospitals closely forward behind advancing forces and support combat operations with effective, far-forward surgical care. A radical departure was that all of the unit's equipment, medical and surgical supplies, and rations could weigh no more than the 29 men could personally transport. Designed to meet a specific problem at a specific point in time, the Portable Surgical Hospital had several shortcomings. First, the weight limitations meant that it lacked much of the equipment that it needed to conduct definitive surgery. Second, it lacked the capacity to hold patients for any length of time, which could often be called for by the tactical situation. Third, the assigned surgeons lacked the skills and experience necessary to meet the demands on the units, as Carroll often sent younger, less experienced surgeons forward, a departure from the Army's experience in World War I, which showed that less experienced surgeons should be kept at larger facilities to the rear, where they could operate under the tutelage of a more experienced senior staff surgeon. And, finally, the Portable Surgical Hospitals had been stripped so lean that they were never truly self-sufficient, and had to rely on other units for life-support. The
Mobile Army Surgical Hospital, developed after World War II, would address these concerns. One-hundred percent mobile with organic vehicles, with 60 beds and assigned nurses, and fully equipped and supplied to provide definitive care, the MASH built on the experiences of the PSHs of World War II. ==List of PSH==