The prince offers to let them spend the night, as it's already grown late, and he's likely tired from both traveling, and from his recent fight. The army should arrive at the site for the battle almost two full days ahead of the trolls, if they push ahrd, which should give him time to prepare, especially if he works while with them on the road. "I think it would do the men well to see someone as powerful as you leading us. If nothing else, the morale boost will help them significantly; a lot of them are furious, as it's their families out there, being slaughtered by these brutes."