Amusingly, what military types today usually wear is a Casio G-Shock. It's hard to break. It's unbothered by water, mud, etc. It doesn't transmit anything, which most "smart watches" do. (Wearing anything that transmits in a modern combat zone is waving a sign that says "kill me now") Solar power keeps it going without attention. There's a minimal light if you push a button. Right tool for the job. Not a status symbol.