This is a 16 inch wrench. gov't issue. I think it must have been for a specific piece of equipment or use, but have no idea what. Anybody have an idea? I got it at a flea mkt. last fall 'cause I'm a sucker for combo tools. I count at least 8 different functions. It looks like aluminum but it's iron. It's marked "US, Joseph Shaw Co. Toledo Ohio" Thanks
Bruce

Oil drain plug and brake wrench?

Looks like a bung wrench.

bung wrench makes sense. there's a place for every conceivable size plug.
Bruce

OP, there's a wrench like yours for sale on ebay. Unfortunately it doesn't say what it is, only specialty wrench.
Another Shaw Tool auction lists an ELL wrench, and the seller says he assumes it's military from before the 1950's, having gone though the Rossford Ordnance Depot in the Toledo area, which was the largest military supply center in the US at the time. (All his info).

I've got a Jos Shaw Co DBE wrench that I know very little about! I kept it around because it was a pair of useful sizes, was USA made, and decent quality.