I found this book in the used bookstore when I was in middle school (1984).
It was already older (published in the 50s or 60s, I suspect). It had a orange/rust colored cover with a very impressionistic sketch of a military scene.
The story follows an orphan who runs away to join the army. He is befriended by a soldier (the name Mr. Putnam stands out) who protects him in camp and on the battlefield. Either the boy or the soldier is wounded (fairly certain it is the man).
Of all the details I remember, there are young girls who makes silk beads that supposed to help quench the soldier’s thirst if they run out of water.