One of the more controversial changes introduced by the B-25H was the deletion of the co-pilot position. The elimination of the co-pilot's seat, armor plate, and controls resulted in a saving of over 300 pounds of weight. At the position of the copilot, a jump seat for the navigator was provided since his position had now been preempted by the forward-moved dorsal turret. General James Doolittle had always questioned the need for a copilot in the B-25 and B-26. However, General George Kenney, commander of the Fifth Air Force in the Pacific, vehemently objected and claimed that he needed the second pilot for long, over-water missions under hazardous conditions. However, General Arnold overruled these objections, and the B-25H was delivered without a co-pilot's position.
The five-man crew consisted of the pilot, navigator-cannoneer-radioman, flight engineer-top turret gunner, waist gunner-camera operator and tail gunner. Three of five crew members had multiple jobs; there was no co-pilot or bombardier and only one waist gunner.
Are you sure the Marines had a B25H with a co-pilot seat or was it a B-25G that had the copilot seat? From what I've been able to find, there wasn't a B-25H with a co-pilot seat and those 75mm cannon equipped B-25s that did have a co-pilot were the B-25Gs.
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