It depends at what stage the town has been under siege for. If it was relatively newly surrounded by troops, than there would be fear, anger, resentment, in the town, people would be fighting a lot because everyone is on edge, more people going to church, etc.
If the siege had been going on for weeks and weeks, then the people would be starving, the food rations getting smaller and smaller, people would start eating their animals, (livestock/pets), if it got really bad, they would start to kill other adults or even their own children for food. There would be death everywhere. And the fear, the fear is ever present. After a time, the fear starts to go away, and they almost tear down the walls and the gates to let the enemies at them. They think that anything is better than watching their families slowly dying the horrible death of starvation. Their will to survive outlives their fear of the enemy.
There would be: - panic - unrest - tightened security - food and water begin to be rationed - every family for themselves - suspicion (could your friend, family member, neighbor etc be a spy?) I hope this helped, let me know in the comments
