What World War II officer
had the nickname "Vinegar" ?

General Joseph Warren Stilwell.

'General Joseph Warren Stilwell had one of the toughest jobs of any American general during World War II. This involved keeping China actively in the war against Japan, while being assigned to two theatres of war, being run by three separate political entities, each with its own interests and goals.He not only had to fight the Japanese, but was torn between conflicting loyalties and responsibilities-a situation not helped by his brusque, no-nonsense manner, which earned him the nickname "Vinegar Joe."'

That's him, "Vinegar Joe" !

Thanks for the answer Jenny !