Whitebeard War Saga

Preparing for War
As mentioned by Momonga, Whitebeard begins making his move towards Marineford to save Ace, Kaido attempts to take advantage of the situation to attack the Whitebeard Pirates. To the horror of the Marines, reports come in that Shanks has intercepted Kaido, creating a dispute between two of the four Yonko. While the two captains end their confrontation with a stalemate, the Marines become greatly anxious of the possible problems that could arise from conflict between the two pirates.[16]

Ceasefire at Marineford

“

I'm here to put an end to this war!

”

Appearing suddenly, Shanks arrives just in time to save Coby from being killed by Akainu. He commends the young Marine for his determination and tells him that with his brave words, he has secured the "seconds of courage" that would change the fate of the world. Shanks then notices the straw hat he gave to Luffy on the ground and picks it up, declaring that he has come to end the war. He tosses the hat to Buggy and tells him to give it to Luffy and he'll give him a treasure map, this of course being a lie, further enraging Buggy when he shrugs it off commenting on how it's been a while since they last saw one another in a calm familiar tone.

When Lucky Roo asks if he's sure if he wants Luffy to leave since he hasn't seen him in so long, he simply states meeting back with him "now" would break their promise. He states to the entire battlefield that if anyone still wants continue fighting, his crew is more than ready to join. Everyone is content with this and decides to stop fighting, he then states to Sengoku that he and the Whitebeard pirates will take care of Ace's and Edward Newgate's bodies.

Shanks takes Ace and Whitebeard and buried them on an island somewhere in the New World. His crew, along with the Whitebeard Pirates attend the funeral to show their respects. He quietly thinks about how Luffy is handling Ace's death, stating that to become a real man, one must know victory and defeat.