Collectively known as the M19 Heavy Tank Transporter, this truck and trailer combination was conceived at the behest of the British in 1941, and was later used by the US Army as well. The prime mover for the combination was the Diamond T model 980 or 981 12-ton truck, known as the M20; the 45-ton-capacity full trailer it towed was designated the M9. The combination saw widespread use during WWII and well into the post-war years. Explores the development, use, and details of these wartime workhorses.