After the destruction of the maelstrom device, Marcus and his squad went to the beach to meet up with Baird and Cole, who promised to bring help, but wasn't expecting the UNSC infinity to be part of that reinforcement. 100 years after the Infinity found Sera and after the alliance that was forged between the C.O.G and the UNSC, 4 ships, that was being commanded by former C.O.G soldiers, FTL drive got damaged in a battle and it sent them to Equestria, but they didn't expect what the inhabitants look like or what they were doing.