The only requirement for the purple heart is being wounded. If you are wounded by enemy action while serving then you are eligible for a purple heart. It doesn't matter whether you were shot while storming a machine gun nest, or you tripped over a land mine while going to take a piss, or an artillery shell hit the edge of the tent you were in causing it to fall over and hit you on the head. All of those things classify. Kurt Vonnegut, for example, is famous for having gotten a purple heart for getting frostbite. Which, to be honest, stretches the definition of the medal a bit but the criteria for awarding it have always varied from time to time.

As for your grandfather, it is impossible to know without additional context what specific injury he got the medal for but the fact that a cook would receive one is not surprising in the least. It could be anything from being injured by artillery, mines, being shot by a sniper, or who knows, maybe he stormed a machine gun nest.

For what it's worth, MTO means "Mediterranean Theater of Operations" which would likely have meant Italy/Sicily or North Africa. 2 Feb 4 could mean Feb. 2nd 1944 (assuming a digit isn't missing).

Well, MTO stands for 'Mediterranean Theater of Operations' but without more information I can't say much.

Did he serve in the Navy? Army?

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