The considerable talents of George Tobias who played many of the kinds of roles here in feature films, usually in support of the leads. He's an amiable sort of lunkhead who can't bear to be parted with his taxi cab Bessie. He's a hack driver in civilian life and sees no reason he can't take his reliable vehicle into the army with him. So he drives her from New York all the way to Fort Knox, Kentucky where he reports and learns all about the driving, care, and maintenance of a tank.
Through all the propaganda and the attempts at wartime humor which don't really hold up well today, we learn a lot about tanks and their use in wartime. This was in fact the great advance in weaponry from World War I and the Nazis learned the lessons better than the Allied powers did.
Gig Young, Richard Travis, and John Litel are also in the short which did get nominated for Best Short Subject in 1941. Today The Tanks Are Coming is a a slightly amusing bit of history.