The entire force of the Navy + the 7 Royal Warlords (Shichibunkai) all assembled at the last remaining unbroken Important Navy Facilities, the Marineford (Marine HQ), after Luffy had broken in and out Ennies Lobbies (Royal Court) and fresh out of Impel Down (Royal Prison). Ace, Luffy's brother and member of the Whitebeard Pirates were to be executed, so Whitebeard, one of the 4 Emperors (Yonkou), gathered all his crew and allies and charged into Marineford. An EPIC battle took place, ending in the glorious, yet tragic and saddening death of Ace and Whitebeard, along with multiple other, but not before being officially terminated by Red Haired Shanks, another of the Yonkou. A series of events (it was not End fight, go train, it had a meaning), took place that set Luffy out of his depression and gave all the remaning Straw Hats the will to train and better themselves, each at elite and extraordinary places with extraordinary mentors. Of course, before it ended, Luffy barged into Marineford again, followed by 1 of the Shichibunkai and the Best Man of the deceased Pirate King, and declared War on the World Governament by declaring he end of an Era, Whitebeard's Era.