This is an idiom that means to go and meet the enemy army for battle. AT: "march against ... March out against" or "Go to battle against ... Go to battle against" (See: [[rc://en/ta/man/translate/figs-idiom]])
"Indeed, they are." The word "See" is used here as an idiom to draw attention to what is said next. The people cannot currently see the enemy army. AT: "They are" (See: [[rc://en/ta/man/translate/figs-idiom]])