The first paragraph of "An Episode of War" is brief, and almost entirely descriptive;

The lieutenant's rubber blanket lay on the ground, and upon it he had
poured the company's supply of coffee. Corporals and other
representatives of the grimy and hot-throated men who lined the
breastwork had come for each squad's portion.

So, the answer to your question is quite succint; the corporals and other men are described as being "grimy and hot-throated", but we can probably glean some other information from this passage;

• The lieutenant is probably in charge of this particular group of men.
• It's probably daytime, and a battle is not taking place; the lieutenant wouldn't be distributing coffee during a fight. It might be morning, since coffee is typically a morning beverage.
• The corporals and other men may be much dirtier than the lieutenant, seeing as he is not described as being grimy. This implies he may be a bit better off, more well-mannered or "cut from a different cloth", as they might say. "Hot-throated" might imply that the men are also louder, more rambunctious, less civilized, or perhaps just hungry.
• "Breastwork" refers to fortifications. "Lining the breastwork" implies that this is a fort of some kind, perhaps on the frontier.