Acctually it is very specific who rebelled. The EAF has been dominated by the Atlantic Federation since the Battle at JOSH-A. The vast majority of soldiers that were left behind there as bait were Euraisian troops. Even before then Euraisia was more rival then ally of the Atlantic Federation. After Dullindal's speach it was the Eurasion fleet that joined ZAFT at Gibralter. The Atlantic Federation is the faction that stayed loyal to Djibril, and are still fighting, though they are crumbling.