Ultimate War (2003 series) #1

The Brooklyn Bridge is destroyed by Magneto who issues a manifesto proclaiming his intentions to subjugate the human race to his Brotherhood of Mutants. The President orders Nick Fury to put his Ultimates into action to capture the mutant terrorists. While several members of the hero team organize rescue operations at the disaster site, Captain America and his team track down and capture several of Magneto’s henchmen. Scarlet Witch and Quicksilver are invited to join the Ultimates in their mission to take down Magneto, though some of the group is suspicious of the mutant siblings, who are, after all, Magneto’s children. Iron Man heads out to Charles Xavier’s school to see if his people are safe from the mutant terrorist; when he finds the school deserted, he concludes that the X-Men have gone over to Magneto’s side.