Civil War: X-Men #1

With the Civil War raging and the fate of the world's few remaining mutants still in question, Domino and Shatterstar show up at X-Mansion to break the 198 out of their forced captivity. Despite the best efforts of the government forces led by Bishop, Sentinel Squad One and the X-Men themselves, they succeed and make off with about half of the mutants. The government makes plans to retrieve the 198 and the four original X-Men (that's \"men\" literally), forego their neutral status and commit to finding the missing mutants first.