Say, that looks like a C-47! What's a C-53?
A C-53 is essentially a DC-3 that at some point was specifically designed for military service. To be crude, it's a DC-3 in fatigues. Unlike the C-47 it does not have big cargo doors, a reinforced floor, or beefy landing gear. The easiest way to spot a C-53 “on the fly” is to look for the single oval entry door on the left side and the small baggage compartment door or the skinnier prop blades as opposed to the fatter wartime paddle blades of the C-47.
Even without the militarization that the C-47 received the C-53 was still a troop transport and participated in combat missions as drop platform for paratroopers, glider tugs and as medical evacuation aircraft.
In the late 30's, the U.S. Army Air Corps was well behind the world in terms of military aviation. US Army Air Corps General Hap Arnold knew this needed to change. At the time the slim budget had to be appropriated correctly for fighter aircraft and more specifically bomber aircraft. The German military got the world's attention however using airborne paratroopers and gliders as effective Blitzkrieg weapons at the beginning of WWII. As a result, orders for troop transports came pouring in. Unfortunately, the demand far outweighed the supply. Once the United States entered the war however the C-47 /C-53 became the workhorse and backbone of the US war effort. At the end of the World War II, General Eisenhower credited the C-47 / C-53 as being one of the four most important weapons credited with winning WWII.