Whitebeard Pirates

The Whitebeard Pirates crew (白ひげ海賊団, Shirohige Kaizokudan) is the strongest pirate crew in the One Piece universe as their captain (Whitebeard) was the only one to have ever tied with Gol D. Roger in a fight. Whitebeard's crew is segmented into divisions as shown below.

Part in the Story
The first member seen is Portgas D. Ace, who decides to see how his brother Monkey D. Luffy is doing during the Arabasta Arc. After easily destroying a fleet of Baroque Works ships, Ace hands Luffy what appears to be a blank piece of paper, which is later sewn to the inside of his hat's ribbon,which is actually a Biblicard and leaves. Biblicard is a card made of nails that can only be found in The New World. Whitebeard himself appears when he rejects a letter from Red-Haired Shanks, stating that if Shanks wishes to speak with him he should do it in person. The World Government fears what would happen if their two crews were to join together, but has currently chosen to just observe their actions.

After Ace chased down the traitor Marshall D. Teach and was defeated, he was sentenced to death at Marineford. As Ace's execution closes in, the entire Whitebeard Pirates, along with their 43 allied crews, came to Marineford and waged war against the entire Marines and Shichibukai.

Pirate Flag


Whitebeard's flag is that of a standard Jolly Roger with a large mustache and a cross behind it. Many high-ranked crew members bare the Whitebeard flag symbol on them including Ace, who is seen having it tattooed on his back and being extraordinarily proud of it.

Originally in the manga, a manji was behind it instead of a cross, while the current version is originally only used in the anime in order to avoid confusion with a swastika, like the ones used for nazi flags. The swastika symbol used by the nazis is not to be confused with the symbol Oda chose to use, though, as the nazi one has the arms of the cross bent at right angles while the Whitebeard one has them bent at left. However, in Shonen Jump #50, Oda commented that from Chapter 434 onwards he would have to use the cross version of the flag in the manga as well, being told to do so by the higher-ups at Shueisha.

Strength
Whitebeard is one of the Yonkou of the second half of the Grand Line, along with Shanks, Kaidou and another unknown pirate. This makes the Whitebeard Pirates one of the four strongest pirate groups in the Grand Line. There are 16 division commanders of Whitebeard's crew each commanding a crew of 100. There is a grand total of 1,600 men in Whitebeard's crew.

Since their captain had managed to fight with Gol D. Roger one-on-one, the Whitebeard Pirates are considered the strongest known pirates in the world of One Piece. Even the normally overconfident Buggy the Clown refused to attack Ace when he was asleep, fearing Whitebeard's wrath. However, whether they are stronger than the three other Emperors, or at the same strength, is unknown. What is known is that the World Government is prepared to use practically all of the Marine forces and the Shichibukai, to fight the crew, after they announced Ace's execution. Even the 23 Marine ships that were supposed to be watching over the Moby Dick (Whitebeard's ship) were instantly wiped out as it started to move. Also the fact that Portgas D. Ace a member of Whitebeard's crew, his capture was good enough to have a spot in the Shichibukai (though Ace's capture meant a lot more than just being a Whitebeard's subordinate, as he is also the late Pirate King Gol D. Roger's son).

Furthermore, according to Blackbeard, a general rule on-board Whitebeard's ship is that any crewmate who happens to find a Devil Fruit is free to consume it (which is why he killed Thatch in order to obtain the Yami Yami no Mi in the first place). From this, it is fair to assume that a certain number of the Whitebeard Pirates possess Devil Fruit powers. Indeed, the top 3 division commanders all have Devil Fruit powers, as does Whitebeard himself. These Devil Fruit powers made the commanders strong enough to stand against the Marine Admirals and Shichibukai. With his Devil Fruit, Whitebeard is able to destroy the world.

Allies


Aside from their own 1600 members crew, the Whitebeard Pirates have many allies from the New World. They all seem to know Ace, at least, and were willing to help when he was about to be executed at Marineford. Each one of them are infamous pirates who made themselves a name at the New World. There seems to be at least 43 of them allied with Whitebeard.

Aside from that, Jinbei of the Shichibukai gives his respect to Whitebeard for protecting Fishman Island, along with his friendship with Ace, and was willing to lay his life down for either of them. Furthermore, with Jinbei being currently allied with the Straw Hat Pirates Captain Monkey D. Luffy, the Whitebeard Pirates can also be said to be allied with the Straw Hat Pirates by extension, even though Luffy doesn't trust Whitebeard enough to just step aside and allow Whitebeard alone to save Ace.

Other Information
The Whitebeard Pirates are divided into sixteen divisions that are then led by a high ranking Whitebeard subordinate. This pirate crew includes Portgas D. Ace commander of the Whitebeard 2nd Division. Blackbeard was formerly a member of this crew in the 2nd Division but left to form his own crew after killing some of his former crewmates. The front part of Whitebeard's flag-ship, the Moby Dick, resembles a whale.

The Whitebeard pirates are famous for taking the concept of camaraderie to exaggerated levels. Whitebeard sees his crew as his sons, and will avenge their deaths—a reason why most pirates would not attack them. This rule is especially true when the one that attacked them is a fellow crewmate. Lastly, Whitebeard believed that even as a pirate, there must be some kind of morality.

Shichibukai Jimbei was heard remarking on power the name 'Whitebeard' had when he stated that after Whitebeard declared Fishman island his territory that the violence on Fishman island stopped.