The thirteenth chapter will take you to the Ghost Town where you will encounter only enemies. You won't see even one friendly citizen, everything what will be living must be killed (except of horses). Brothers will get special and unique tasks as well, Thomas' one will a bit more complex.
After taking control over your character, you will find yourself on the top of the hill near the town. Mount your horse and go towards building. On your way you will encounter a trader. Buy there different gun than the sniper rifle because that weapon will be useless in this chapter.
After reaching your brother, leave the horse and follow him.
In that way you will get to the place where you'll be able to hear noises. It will come from the nearby building, the game will show the way [secret].
Then, your job will be enter that hideout and kill all opponents inside. In order to do that, playing as Thomas you will be forced to get to the balcony, playing as Ray you will simply brake down a door (more details in "Bothers" subsection).
Both on the ground floor and the first floor there won't be many enemies and besides they won't act cleverly so you will kill them without any problems (if you do this very fast they even won't start shooting).
Leave that building in go towards another in which more opponents is hidden (the parallel road). The fight outside will be a bit more difficult from those inside. The opponents will appear from the left side as well as the right one.
Before you will enter the building [secret], you can grab a nearby lamp and throw it into the house. In that way you will "paralyze" them for a moment what will make that extermination a bit easier to accomplish (of course only those on the ground floor).
The next place where you should go is the big building in the end of the main road. Before you will reach it, three men will attack you. After killing them a short cut-scene will be triggered.
When the scene will come to an end a shooting will start. Enemies will appear on the nearby roofs (your brother will get on the roof to help as well)
At the one point enemies will start throwing dynamite from the roof of the biggest building. Be aware that this moment will start Thomas and Ray's special tasks. Description as usually in "Brothers" subsection.
After killing enemies from the outside and windows, one of them will use a heavy machine gun inside - on the ground floor - and will destroy walls. When that happen hide behind a cover and wait for a perfect moment to kill him.
Then, approach the building and trigger Cooperative Concentrate Mode. Inside it [secret] will be a lot of opponents and if you do not kill all of them during slow-mo, hide behind the wall and finish them in more typical way.
When all opponents will die try to take a stairs. Doing that will start another cut-scene and after that you will take part in another duel. I hope that I don't have to remind you how to win.
After winning take the stairs and watch another scene. You will see how your friend die.
After the cut-scene enter the balcony on the left side and before you will jump down, kill all opponents.
Then, go towards the black barn, next to the place where a moment ago opponents tried to kill you. Inside it [secret] you will encounter another enemies.
Leaving that barn on the other side you will find yourself on the graveyard. At the end of it a small church is located. Before you will reach it, you will be forced to kill a guy with the heavy machine gun (next to the entrance to the church). That task is not very difficult because the graveyard will provide you will many covers.
After reaching the church [secret] wait until the main antagonist throw out from it a few dynamites and destroy the building. Then, grab the machine gun and start shooting into the bell. In that way the whole building will collapse.