I'm still saying he should have just sneak attacked them. You can't tell me, he wouldn't be able to infiltrate the fort without even waiting any further minute. Even if he wanted to take them head on (stupid because of witnesses of his "evil/rebellious" deeds/he took the route of the most bloodshed), why did he talk to them that much in first place? Take out the head officers, search for the children or torture the left soldiers, if you can't find them. It's rather easy. I know the twins are in danger, but giving them time to adjust or get ready to kill the kids on the spot, puts them at bigger risk.