The surname "Chaffee" was of British origin and was later adpoted in the US Army. Planned as a replacement for the Stuart, it combined a ultra-light 75 mm gun, initially developped for aircraft, with the running gear of the Hellcat M-18, the fastest tank of World War II.
Put in production too late to play a major role in Word War II, it had time enough to prove its qualities as to mobility and firepower (for its category). It was issued to the British and the French used it among others in Indochina. Chaffees stopped the rush of the T-34/85's in Korea in 1950.
Its only big drawback was the insufficient armor.
