Raid on the British Men of Letters compound

The Raid on the British Men of Letters compound was a vampire raid on the British Men of Letters compound led by the Alpha Vampire in response to the British Men of Letters slaughtering the American vampires.

Background
Shortly after the Darkness left the Earth, the British Men of Letters made their presence known in America. Led by Mick Davies, the organization began attempting to recruit American hunters to create "a world without monsters" without much success. Mick eventually succeeded in recruiting Mary Winchester, but otherwise failed to recruit "the top-shelf" of American hunters, only getting hunters such as Pierce Moncrieff.

After recruiting Mary, the British Men of Letters had her steal the Colt from the Prince of Hell Ramiel for them, an operation that was successful. However, the Colt came with no bullets and the British Men of Letters lacked the knowledge of how to make more, rendering the legendary gun useless to them.

The British operation eventually set out to wipe out all vampires in America, something they would come to call Project V Project V succeeded in wiping out all but eleven of the vampires in the Midwest Region, drawing the ire of the Alpha Vampire due to the number of his "children" that were being slaughtered. Having learned of the location of the British Men of Letters compound from Pierce, who was in reality a mole for the Alpha Vampire, the Alpha Vampire gathered the surviving Midwest vampires for a raid on the compound.

Battle
The vampires start their attack by drawing the attention of McGillicuddy, the British Men of Letters operative guarding the gate to the woods nearby. While McGillicuddy is distracted, the rest of the vampires come from behind and kill him.

As Serena Colman starts to wonder where McGillicuddy is, the vampires raise him in front of a security camera and then use McGillicuddy's handprint to unlock the gate. The group gathered inside the compound realize that its the vampires from the Morest Hotel and Mary quickly orders everyone to fall back, secure all exits and to not engage while Sam orders the compound locked down.

Hearing Mary's orders and spotting the vampires, a guard locks himself in the cage surrounding the entrance to the compound itself and unlocks the door, but as he gets through it, a vampire rips open the roof of the mesh cage and forces his way inside before the guard can close the door. The vampire and the Vampire Nest Leader attack and kill the guard. As Sam and Mary rush to help, Serena and Alton Morehead lock the doors to the interior part of the compound and with Mick Davies and Pierce Moncrieff, barricade themselves in the control room. Sam and Mary arrive too late to save the guard, but Sam knocks the nest leader unconscious and Mary kills the other vampire. Sam quickly secures the door to the cage near the entrance and the entrance door itself and stops Mary from killing the nest leader so that they can interrogate him instead.

As two vampires begin breaking in through the main entrance and the rest spread out to surround the compound, Mick questions how the vampires found them and even knew who the British Men of Letters are. The nest leader informs them that the Alpha Vampire told them and is back to save all of the American vampires. While the British Men of Letters believe this to be impossible as their intelligence has the Alpha Vampire in Morocco for at least a decade, Sam informs them that this is wrong as he met the Alpha Vampire in Hoople, North Dakota five years before. As the nest leader taunts them that they are all dead, Mary kills him.

With their situation growing dire, the group begin discussing the options. They quickly realize that they can't call for help and don't have time to wait anyway as the compound isn't built for defense. As well, only Mary, Sam and Pierce have ever actually killed anything. Taking inventory of their weapons, the group quickly discovers that they also possess minimal armaments, the rest being in the armory, including the AVD. Mary suggests setting off the AVD in the vents to act like a bug bomb and maximize coverage, but Sam knows that at most, the AVD will only hurt the Alpha Vampire and can't kill him.

Knowing their limited weaponry won't suffice against the Alpha Vampire, Sam asks about any stronger weapons the British Men of Letters possess. At Mary's request, Mick produces the Colt, the one weapon they have with any potential to harm the Alpha Vampire. Mary finally admits to Sam that she stole it from Ramiel while Mick informs him that the gun won't work as they have no bullets for it. After recovering from his shock at seeing the Colt again, Sam provides Mick with the ritual given to him by Bobby Singer for creating new bullets and leaves Mick with Alton and Serena to perform it as he, Mary and Pierce go to get the AVD from the armory.

As the three American hunters make their way to the armory, they come under attack by two vampires that have managed to penetrate the compound. Sam sends Mary and Pierce to the armory through a different path while he stays behind to deal with the vampires. Reaching the armory, Mary is able to retrieve the AVD, but is then knocked unconscious by Pierce who is really working for the Alpha Vampire. Pierce destroys the AVD and signals the Alpha Vampire that it is all clear to enter.

Moments after Mick completes the ritual to create new bullets for the Colt, Pierce returns, demanding entry and claiming that things are bad outside. After Alton lets Pierce in, the Alpha Vampire kills Alton from behind with his claws and Pierce reveals his treachery. Serena desperately attempts to attack the Alpha Vampire, but he easily overpowers Serena and drains her of blood. Mick is able to take advantage of this moment to close the case containing the Colt, hiding the gun from the sight of the Alpha Vampire and palms one of the new bullets for it. The Alpha Vampire reveals that he has been paying Pierce well to keep him hidden and is aware of the British Men of Letters operations. While the Alpha Vampire doesn't care about what the British operation does in England as "its England", he feels that America is his home and he wants to stop their efforts there. The Alpha Vampire tells Mick that he intends to restore the compound's communications, force Mick to contact his superiors and concede defeat at which point the Alpha Vampire will drain Mick live on camera.

At the same time, Sam kills the two vampires he encountered and finds Mary as she awakens. The two return to the control room where Mary knocks Pierce unconscious and Sam retrieves the empty Colt and takes aim at the Alpha Vampire, allowing Mick to escape his clutches. As Mick demonstrates to Mary the Colt bullet he has palmed, the Alpha Vampire recognizes the Colt and claims to Sam that he is one of the five things the gun can't kill. Sam, however, recognizes that the Alpha Vampire is bluffing as if it were true, the Alpha Vampire would've already killed Sam. The Alpha Vampire tells Sam the Colt can't save everybody, causing Sam to respond that his intention is not to save everybody, but himself and Mary. Sam reminds the Alpha Vampire that in the past, he has allowed Sam and other hunters to kill vampires without repercussion. The Alpha Vampire acknowledges this, stating that he has so many children "what's a few here or there?" Sam suggests that if the Alpha Vampire lets him and Mary go, they can return to hunters and vampires fighting on regular terms, "a fair fight." Considering this, the Alpha Vampire asks about "the Brit" and Sam agrees to let the Alpha Vampire have him. Questioned by Mary as to his actions, Sam tells her that he is "picking a side."

Apparently enraged by Sam's actions, Mick attacks him, in reality using the opportunity to slip Sam the Colt bullet. Sam quickly throws Mick off of him and Mary attacks the Alpha Vampire from behind, giving Sam the chance to load the bullet. After throwing Mary off of him, the Alpha Vampire calls Sam's bluff, having realized that the Colt wasn't loaded. Sam asks if the Alpha Vampire is sure in his assertion and the Alpha Vampire realizes what Mick and Mary did. As Sam cocks the Colt, the Alpha Vampire calls him a "clever, clever boy" in respect. Sam shoots the Alpha Vampire through the head with the Colt. As the legendary gun's power works on him, the Alpha Vampire chuckles before dropping to the ground, dead.

Following the death of the Alpha Vampire, Sam and Mary dispatch a few "stragglers" and the surviving vampires retreat, ending the battle.

Aftermath
Following the battle, Mary reconciles with Dean who had been angry at Mary for joining the British Men of Letters operation until he nearly lost her. Arthur Ketch, having been away attempting to recruit Dean by taking him after the last vampire nest in the Midwest, takes Pierce Moncrieff for punishment for his actions, something Mary and Sam are pleased about. Sam also decides to sign on with the British Men of Letters, stating that the death of the Alpha Vampire proves the good they can do in the world.