X-Marathon would like to wish its readers a merry X-Mas, and peace and goodwill to all mutants.
Uncanny X-Men's Mutant Massacre issues are #211-#213.
Our Westchester team are having a quiet but productive day, when a Morlock (who doesn't get named here, but he looks like a mole so let's call him Mole) comes from below, bearing news of the Marauders' attack on the Morlocks. Or rather, he passes away, but not before Psylocke gets the skinny out of his brain. Good thing they had a teep.
Storm rounds up the team (minus Magneto) and they immediately teleport - courtesy of Magik - to the Morlocks tunnels. They land right by some causalities, including Callisto. They are soon attacked by Vertigo and Riptide. Nightcrawler (who was hurt badly in the battle with Nimrod and is still recovering) takes Vertigo out, but is then nearly killed by Riptide, who runs away with his fallen comrade.
Magik is sent back to base, with Nightcrawler and the other wounded (the art here only shows one body other than Kurt, but we have to assume there are more?), but is ordered not to bring reinforcements and implicitly not return - an odd decision by Storm, and one which is surely a mistake.
Throughout the issue there is more fighting and massacring. Wolverine gets a scent of X-Factor, also in the tunnels that day (see the posts either side of this), including Jean, who logically must have a different scent to Maddy; this is confirmed by a sighting of one of Cyclops's optic blasts. They do not get to talk, as rocks fall. During the fight, Kitty becomes permanently phased. A second evacuation is made, with everyone they can muster, except Wolverine, who is left behind, with instructions to bring one prisoner. Storm very strongly implies that Wolverine should kill everyone else.
Wolverine goes a-huntin', and eventually finds a Marauder, by the name of Sabretooth. In those two pages (issue #212 13-14), everything we need to know about their pre-existing relationship is lain in front of us. They're rivals, but Sabretooth thinks Wolverine is beneath him. And we get our first hint as to who has ordered the massacre: someone called "Mr. Sinister".
At the mansion, things are not going very well. Storm is having a crisis of leadership, but is given a pep talk by Callisto, of all people. Morlocks are still dying, they daredn't use a normal hospital, and Colossus, despite Magneto's efforts, is in paralyzed. Wolverine never gets his prisoner, and leaves Sabretooth buried under rubble (but under no illusion of his death), but gets a prize survivor: Healer, who will help with the survivors. They make a final trip back to check the tunnels: Magneto, Storm, Wolverine and Callisto, but find nothing other than Thor's cauterisation of the tunnels. Has this killed the New Mutants, who disobeyed instructions and went down there? Well, that's better answered in New Mutants.
While that was all happening, Sabretooth was making his way to Salem Center. First he attacks Rogue, then Psylocke (incidentally, Psylocke says here that Kitty is "half [her] age", making Psylocke 28/29, and possibly older than pretty much all the other X-Men? Huh. Never figured that one.) Psylocke puts up quite a fight (even in her pre-ninja days), but she's not exactly a match for Sabretooth on her own, and has to be saved by Storm. Finally, it's time for the main event, and Logan and Creed fight again, while Psylocke probes Creed's mind for any information about the Marauders and Sinister she can get. Wolverine is given the all-clear, and launches them over a cliff-face. So, that's Creed properly taken care of, right? In a short epilogue, they discuss regrouping at Muir Isle, which probably makes sense, and agree that Betsy should join the X-Men.
So, what has happened here is that the X-Men have failed their fellow mutants. Hundreds are dead, the worst anti-mutant incident yet, and practically on their home turf. Three of the team themselves are critically injured. Why did they fail? Was it because they were simply outgunned, or is it due to mismanagement? The evacuation was not very well handled, and one wonders whether Magneto and Magik had been involved whether more lives might have been saved. And in the middle of this, Storm had a meltdown. Charles Xavier would have been very disappointed.