Armor, by John Steakley.

The premise: a first time soldier, Felix, is given an incredibly dangerous first assignment. Tasked to scout humanity’s power-armored push into the desert planet Banshee, his highly advanced, futuristic force lands in the boiling nest of a highly dangerous alien species that immediately attacks them in endless overwhelmning waves. Pushed to the brink, Felix must dig deep within himself to find a way to survive until earth’s decimated fleet can send back a ship to retrieve the desperate remnants of their invasion force…

A surprising novel. It has a sterling pedigree, but there is a narrative swerve early on and it also introduces another unexpected character. I don’t know where the story is going now, but it’s damn interesting.