The train bombing attacks of 2041 is described in the Black Earth timeline of events. Here is the relevant extract.
The first Hub, Earthen Springs in coastal Virginia, is ready to accept the first migrants. During the year newly set up train lines deliver hundreds of thousands of citizens to their new homes. As the end of the years drawn near, 500 people boarding a train set to take them to Earthen Springs is bombed killing everyone on board. The People’s Rebellion take responsibility for the strike calling people to offer their solidarity with the Exiled nations and forsake the UEF and its Hubs. The People’s Rebellion becomes the number 1 terrorist organisation in the eyes of the UEF reciprocating with rigorous surveillance, arrests and even torture of any one suspected with collaborating with the People’s Rebellion.