What does the phrase “dead man” (or soldier) mean and Where does it come from?

“Dead soldier” means just a liquor bottle, or, perhaps nowadays, can, that is empty; hence, worthless, good for nothing, as a dead man or soldier on a battlefield would be.

The term was recognized in A New Dictionary of the Terms Ancient and Modern of the Canting Crew, printed about 1700, and must certainly have been used many years earlier to have received a listing in that collection.