Portogas D. Ace
ポートガス・D・エース
Ace early appearance!
Ace's pursuit of his former subordinate Blackbeard for the murder of their crewmate Thatch led to him being captured after their duel on Banaro Island, and he was turned in to the Marines, who held a public execution for him on Marineford due to his heritage; this triggered the Summit War of Marineford. While freed from bondage, Ace would ultimately die at the hands of Admiral Akainu while protecting Luffy. Ace initially intended to take Whitebeard's head but was defeated. Whitebeard invited him to be one of his sons, which Ace vehemently refused; despite this, Whitebeard abducted the entire Spade Pirates onto his crew.
After trying to assassinate Whitebeard many times, Ace was eventually drawn in by Marco's description of the love the Whitebeard Pirates bore for their father. He decided to give up on his struggles and take up Whitebeard's symbol on his back; this tattoo became his greatest pride and joy.
Ace held great respect for his captain. As far as Ace was concerned, Whitebeard was the greatest pirate alive, and even went so far as to describe Whitebeard as a type of father figure.
Ace was a loyal crewman and commanded the 2nd division of the Whitebeard Pirates. It is revealed that Thatch was one of the first of Whitebeard's crew to interact with him and they appear to have been good friends. Ace and Marco also seemed to have a close friendship due to Marco explaining the bond between Whitebeard and his crew. Marshall D. Teach, who later became Blackbeard, once served as a member of the 2nd division under Ace and they are shown eating together in flashback with Blackbeard encouraging Ace to become 2nd commander. The Whitebeard Pirates were revealed to be very fond of Ace and unhesitatingly vowed to rescue him from his execution, as seen when they shouted out that they would not forgive anyone who hurt him.
Ace in Alabasta

Whitebeard Years
Whitebeard seemed unconcerned about Ace's hunt for Blackbeard and remained grounded that it was Ace's duty to execute the traitor, regardless of the heavy warnings he received from Shanks. It was revealed however that Whitebeard himself was troubled about Ace hunting Blackbeard and gave him no such orders, but Ace stubbornly set out anyways to hunt down his traitorous former subordinate. Even so, Whitebeard took responsibility for Ace's decision and claimed that it was under his orders that Ace went after Blackbeard.
Whitebeard immediately mobilized his crew and his subordinate crews after hearing about Ace's imminent execution. The Whitebeard Pirates reached Marineford, along with many allied powerful pirate crews, and were at war with the Marines and World Government.