Corvo as adept at avoiding notice but that skill wasn't needed here. Everyone was to busy fighting with weapons even a Tallboy would have difficulty matching. Those big guns were spread out, the men isolated. Perfect target.
Corvo began running, using blink to cross distances while staying out of sight before coming to a stop in cover. He flicked his sword out, spun the hilt around before the blade appeared and he held it in a reverse grip. Peeking around the corner he found his target and used Dark Vision to count the soldier. 3. Should be easy enough, no matter how good a soldier may be he can't watch his back all the time.
He slunk around, drawing upon the rear of the three men. Non-lethal if possible. He watched from close-by as he waited for one of the men to split off.