To meet a 1953 post-war US Navy requirement for a high-performance multirole flying-boat, the Glenn L Martin Company offered its very advanced Model 275 design. The first XP6M-1 prototype was flown on 14 July 1955, the second following on 18 May 1956, and Martin received orders for six pre-production YP6M-1 boats powered by Allison J71-A4 afterburning turbojets, each developing a maximum 13,000 lbs of thrust. Successful flight testing led to an order for 24 production P6M-2 aircraft, which differed primarily by having 17,000lbs of thrust from the newer non-afterburning Pratt & Whitney J75-P-2 turbojet engines. However, the contract was cancelled on 21 August 1959 after only three had been built and these, together with the YP6M-1s, were scrapped at a later date. They were the fastest flying-boats ever built!