Fort Mercer

 is a location featured in Red Dead Redemption in the Río Bravo region of the New Austin territory. Fort Mercer is associated with an outlaw hideout, and is the location of Bill Williamson before he flees to Mexico.

Background
Fort Mercer might have been a fort used during the Mexican-American war as it is near the border with Mexico. Jake speculates that the soldiers abandoned it because they moved up north to fight Native Americans.

It is an important storyline location, as it is here that Williamson remains protected in the fortifications alongside his outlaw companions. Naturally, it is the setting for the Leigh Johnson mission "The Assault on Fort Mercer".

Storyline
Marston seeks out Williamson to appease the demands of Agent Edgar Ross, and during a verbal confrontation where Marston appeals to Williamson to surrender, to which he denies, and fires upon Marston, who is then severely wounded. After rescue and recovery, thanks to Bonnie MacFarlane, Marston starts to organize a raid on the fort. Marston's plan requires the assistance of various characters: Marshall Leigh Johnson, Nigel West Dickens, Irish and Seth Briars. Each character offers different resources and abilities for Marston to complete his mission:
 * Leigh Johnson provides his skills as a veteran gunfighter, as well as the services of his deputies Jonah and Eli.
 * Nigel West Dickens arranges an armoured stagecoach to assault the fort.
 * Seth Briars provides a unique distraction for outlaws guarding Williamson.
 * Irish supplies Marston with a mounted machine gun.

Single Player
After Williamson has been cleared from the fort, it is available as a standard gang hideout later on (after you are able to return to the U.S. from Mexico). The Banditos have now taken over.

Leon Galindo will be outside the walls, at which point he will help the player climb over the wall. Climb up, kill several banditos, drop down and open the front gates for him. After this, simply kill all remaining banditos in Fort Mercer, resulting in the 3 bandito Leaders (enemies with slightly more health than regular ones) will burst out of the treasure room. The hideout is complete once the Gunslinger enters the treasure room too. Also, a Semi Auto Pistol is located on the boxes in the treasure room and take all the treasure. There is also a safe on the upper level of the fort that can be cracked, however, doing so without wearing the bandana will result in a loss of 100 honor (as with any other safe).

Occasionally, the Gunslinger will get stuck behind a wooden rack-like object leaning against a wall. Simply run into this object to make it fall over and he will continue on.

There is a bug in which after introduces himself he will stand motionless making you unable to proceed.

Oddly enough if you go to Fort Mercer before driving Williamson out you can see several Banditos standing around inside, near the top of the walls. You can lasso them and drag them off of it if you're in a good enough position or simply shoot them. Killing them will give no honour change and will add a Bandito kill to your stats.

Multiplayer
In multiplayer Free Roam, the fort is occupied by the Bollard Twins Gang. The LeMatt Revolver is also located here, in a crate on the roof of one of the rear buildings. There is also a Gatling Gun on the roof of the fort. The Free Roam mission requires the player to simply kill all the bandits in the fort, as well as the Bollard Twins Gang Boss. Among the gang members defending the fort are Gus Ballard, who may appear multiple times, and Slink Bradshaw, a NPC infamous for his superb marksmanship.

Farmer MacGuffin's daughter must be rescued from  in the Outlaws to the End Co-op mission &quot;The Kidnapped Girl&quot;.

Undead Nightmare
In Undead Nightmare, Fort Mercer is a permanent Safe Zone, and can never be overrun with Zombies. However, there is a constant horde of Zombies surrounding it at all times, making it very difficult to enter or leave. This is also one of two locations that the player can begin the Missing Persons activity.

Trivia

 * Fort Merceris a real fort that was built during the American Revolution. It sits on the banks of the Delaware River and was headed by George Washington.
 * Fort Mercer is very similar to that of Fort Diego's layout.
 * It is possible to duel the gunslinger, Leon in single player.
 * Mercer comes from the Old English Merc or Myrce meaning "Borderland". This is plausible as Fort Mercer is on the US-Mexico border.
 * During the Exodus in America mission, Jake will tell the player that, although Fort Mercer has been abandoned for years, it was originally occupied by American soldiers during the Mexican War. He says that even though he heard they left to fight Indians in the North, it's possible they "got tired of being soldiers and went looking for gold, you know how things is." It's possible that this is a reference to the group of soldiers who hid the gold found during the Treasure Hunter Challenges, considering that Fort Mercer has a treasure room located within its walls.
 * Fort Mercer also has the distinction of being the only gang hideout to be occupied by four different gangs throughout the game: In single player, Bill Williamson's Gang followed by the Mexican Banditos; in Multiplayer Free Roam, the Bollard Twins Gang; and in Cooperative, Walton's Gang.
 * In the Undead Nightmare DLC, Fort Mercer is referred to as a 'safe zone' instead of just 'safe'. This is probably because it is inaccessible to the undead
 * Very rarely in Undead Nightmare, players can hear something getting hit inside the fort. This turns out to be an Undead that somehow got into a fort. This happens usually at a tower with two soldiers in it. For some reason, the two soldiers do not fire at the Undead attacking them and are often dead by the time you get to the quarrel.

Achievements
Fort Mercer is associated with several achievements:

Fort Mercer Fort Mercer