Background

Sean Cassidy (also known as Banshee) was a broken man. After the death of Moira MacTaggert—long-term ally of the X-Men and former lover of Banshee—and the closing of the Massachusetts Academy, home to Generation X for which he was a former headmaster of the group, he felt he had failed at everything in his life. He began to reevaluate the things in his life, and among those things was Charles Xavier's dream of peaceful coexistence between humans and mutants. In all his years of fighting alongside the X-Men, was there any real change that was enacted? With that thought, Banshee began to re-envision Xavier's dream in a daring new way: why not use mutants as a police force to regulate the activity of other mutants instead of waiting for a crisis to arise? With an abandoned A.I.M. facility, his links to Interpol, and the help of some of his former friends and pupils Banshee created the X-Corps. The force's goal was to police the mutant population in Europe.

Along with Multiple Man, his former students Husk, Jubilee, and M, former Alpha Flight member Radius, and one-time interim X-Men member Sunpyre, he formed the basis of his group. However, the distinct element that separated this group from other X-Men teams, was the inclusion of known terrorists, such as Avalanche, Blob, and later Fever Pitch. Originally, Banshee kept these supervillains in line, with the help of Mastermind. Banshee had captured her and manipulated her illusionary powers to keep the villains under his control. Also as a "guest" was the enigmatic Abyss, who was being studied by Sunpyre.

Exploits

The X-Corps didn't operate as a long term group. The team recruits Mystique, who was posing as a potential new member named Surge. Because of her shapeshifting abilities, Mystique is able to move secretly around the headquarters and she stumbles upon the captive Mastermind and allies herself with the entrapped woman. Together, they are able to free the minds of the villainous X-Corps members, as well as control several duplicates of Multiple Man, and use them in an assault on Paris. In the name of mutant superiority, the group incurs some massive damage to the city including the destruction of the Eiffel Tower. Thankfully, the X-Men, along with the heroic members of the X-Corps, are able to put an end to their rampage across the city.

Aftermath

Unfortunately, there are several casualties of the battles. The villainous Avalanche opens up the ground beneath Radius, seemingly killing him, though it is later revealed that his force field saved him. Sunpyre, acting as the group scientist, is brutally murdered by Mystique during her ascent to power. Even Banshee is incapacitated as Mystique stabs a knife through his throat, the source of his sonic powers. Finally, Mystique is sucked into the interdimensional void of Abyss, not to be seen for several months.

With the injuries sustained by Banshee and the damage to the city of Paris, the group was shut down, while some of their remaining resources and members—such as Multiple Man and M—were moved to the Paris branch of Xavier's X-Corporation.