The Vultee P-66 Vanguard was an American-made fighter originally ordered by the Swedish Air Force as the J10. Following an export embargo, the aircraft were briefly intended for the RAF as the Vanguard Mk.I before being diverted to the Chinese Air Force under Lend-Lease. The P-66 was powered by a Pratt & Whitney R-1830 radial engine and featured a distinctive, tightly cowled nose designed to maximize aerodynamic efficiency. In China, the Vanguard served with the 3rd and 5th Fighter Groups, providing critical air defense against Japanese forces during the middle years of the war.