I take it you found that definition in the dictionary? It is correct, basically. A trench coat is a kind of military-style raincoat or light overcoat. You can find "trench coat" in the Word Reference dictionary.
Yes, those are trench coats. They are military-style coats, not military coats as such. The cut/style of the coat is similar to that of military coats. Did the dictionary you looked in define it as a military coat? And have you had a look at the definition in the Word Reference dictionary?