The "13" gag was employed twice in the cartoon Donald Gets Drafted, released on this day in 1942. Donald's draft notice cites order number 13, and he subsequently reports to Draft Board No. 13.
Also of note in the short--the draft notice reveals Donald's middle name to be Fauntleroy. And some of the sidewalk posters outside the Draft Board are significantly similar in style to designs produced by Walt Disney himself while with the Red Cross in France at the end of World War I.
Images © Walt Disney Company