John Marston goes to Fort Mercer & runs into Bill WIlliamson. He makes a plea with him to surrender and come with John as a chance to "save" him. To John's surprise 2 more men reappear from behind the wall and one shoots John. Bonnie MacFarlane rescues John and helps bring him back to health.

After running into Bill Williamson again, John & a few others decide to raid Fort Mercer. When they clear out the fort Bill is nowhere to be seen. Word is he headed to Mexico. John Marston crosses the river and tries to look for him.

After doing a bunch of running around and capturing Javier Escuella, he gets tipped off about something going on in Escalera.

The Mexican Army has executed many rebels in Escalera and has caught Abraham Reyes. John Marston arrives to see the citizens fighting the army, and eventually finds a tied-up Reyes, about to be executed.

Luisa Fortuna tries to save Reyes, only to get shot, and Marston avenges her by killing two of the soldiers watching over Reyes, who killed her. The remaining one, Raul Zubieta, challenges Marston to a duel. Marston wins and frees Reyes. After freeing many rebel prisoners, the rebels launch an all-out assault on Escalera.

Once you've taken care of the incoming forces, move back into the fort and join up with Reyes. As Reyes' rebels breach through the door, Allende will be fleeing in a stagecoach with Bill Williamson. Head down the stairs behind the house and kill the three soldiers still left behind. Get on a horse and follow Williamson and Allende.

There are two guards on horses behind the cart, as well as the guard on the Gatling Gun. Take them all out before killing the guard riding shotgun, as he'll also be firing at you. Riding sideways will make it harder for the Gatling to kill you. Either shoot all the horses to make the cart stop or, even simpler, just kill the driver with a well aimed rifle head shot to make the wagon slow to a stop.

Alternate method: It is possible to kill all guards from the balcony as soon as you exit onto the veranda. The stagecoach will be riding away to your left. With your Rolling Block rifle, use dead-eye and snipe the guard riding shotgun, the driver, the Gatling Gun's guard and the two horsemen. The stagecoach will then stop and no chase will be necessary.

Once the stagecoach has stopped, Allende will try to buy his freedom by handing over Williamson. The player can then decide to either kill both of them, one of them, or neither of them, where whoever is not killed by John will instead be shot dead by Reyes.

Reyes invites Marston to accompany the rebels in marching on the capital to overthrow Sanchez, but John declines as he must return to Blackwater.