It seems to have been used in the 40s to 60s (in several countries), probably under the impression of WW2 when many civilians had to be turned into soldiers real quick.
Later examples are rather rare.
edit: Another example, from a book:
http://i26.tinypic.com/t8rcwz.jpg
it reads:
The squad leader
The platoon leader
The company leader
It's incredible how much this simple 50's graphic says.
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