The first of the Army's Christie-type tanks, which they put a lot of effort into testing in the 1930s, came in two designations: Convertible Medium Tank T3, and Convertible Combat Car T1. This is one of those two vehicles, though in fairness, we're not quite sure which. After editing, I'm mostly leaning to the idea of this being a T3 which was converted to have the machineguns in the same manner as the T1, which seems to be unreported in the books, mainly due to the period photograph at 24:55 which, if so, simply did not have the machinegun mounted at the time.
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About The Chieftain
The Chieftain (Real name Nicholas Moran) is Wargaming America's resident tanker and amateur historian.