Sneaking into the outer section of the fortress won't be difficult; there's enough people there, and few enough guards, that's it'll be pretty straightforward, and easy to lose himself amongst the bandits and their families and camp followers, inside. Getting into the actual fortress, on the other hand, looks like it might be trickier, but he'd need to get closer, to confirm that suspicion.<br/><br/>The population of the outer town looks to be about fifty or so, but judging from the supplies being stored, and the guard rotations, it's likely there's at least another fifty inside the fortress, and they're likely all combatants.