Missing Staff Sergeant Charlie

Inside El Nath, I found Master Sergeant Fox, who seemed to have crashlanded here. He asked if I can find 3 of his men and if they are doing their job whereever they are. The ones I need to meet up are Staff Sergeant Charlie, Corporal Easy, and Sergeant Bravo, and they should be around Ossyria. He'd prefer that I meet them in the order of their ranks... that sounds pretty difficult to me ...