The Marines are soldiers of the World Government in One Piece. As the Straw Hats' most persistent enemy, their stranglehold over the entire planet makes them a formidable and pervasive threat. Given the Marines' presence and institutional power, it's little surprise that they won at numerous points throughout the anime.
Such victories helped establish their credibility, which was especially important given the series of increasingly ridiculous power-ups Luffy received. In the end, there's an excellent reason why other nations were intimidated into joining the World Government despite a lack of interest to do so.
10 The Marines Prevented Vivi From Joining The Straw Hats
After adventuring with the Straw Hats and defeating Baroque Works, Vivi wanted to join the crew full-time. They agreed to rendezvous at a meeting point so that she'd be able to slip away, unbeknownst to the rest of the kingdom.
However, Vivi realized that if she agreed to work alongside Luffy, it would put the rest of Alabasta at risk. In this regard, the Marines were able to prevent what could have been a powerful ally simply through the threat of violence alone.
9 There Were Almost No Survivors In The Destruction Of Ohara
When the World Government caught wind of Ohara and its study of poneglyphs, their action was decisive and brutal. They sent an entire armada of ships to obliterate the scholars in a fiery inferno. Just as it seemed as if some refugees would escape on a ship, Akainu sank the vessel and delivered them to their watery graves.
Ultimately, knowledge of the Void Century was suppressed so efficiently that the government had nothing to worry about. In the end, Nico Robin was the last surviving translator, making her an invaluable part of Luffy's team.
8 The Marines Captured Doflamingo At Dressrosa
Although Luffy was technically the one to defeat Doflamingo, it proved a major boon for the Marines. Fujitora had desired to destroy the Warlord program, and Doflamingo proved so corrupt that there was nothing that could justify its continuation.
Imprisoning Doflamingo within the darkest reaches of Impel Down had a second advantage. It meant that whatever secrets he possessed about Marie Geoise would remain buried with him. So long as he is in Marine custody, Doflamingo will never be able to enact his plans for complete destruction and destabilizing the world order.
7 Garp Defeated Chinjao With One Punch
As one of the few people alive to use Conqueror's Haki, Don Chinjao was an incredibly powerful pirate. He used his head to drill at opponents, with few capable of withstanding its direct impact. During a fateful encounter, Chinjao and Garp crossed paths.
Although Chinjao attempted to use his iconic drill-based technique, Garp smashed his head so profoundly that it bent his skull out of proportion. This prevented Chinjao from retrieving his treasure and made him spend the next thirty years resenting his arch-nemesis. In the Dressrosa arc, he took out his unresolved vendetta on Luffy.
6 Momonga Convinced Boa Hancock To Help At Marineford
Vice Admiral Momonga arrived at Amazon Lily to request Boa Hancock's assistance at Marineford. She only agreed to allow Luffy as a better opportunity to liberate Impel Down's prisoners. Regardless, this exchange ultimately worked in Momonga's favor.
Not only did it prove that Momonga could still control the Pirate Queen, but it also prevented an all-out war between the World Government and Amazon Lily that they couldn't afford on the eve of Whitebeard's attack. Although only a vice admiral, Momonga's composure and steadfastness worked to his masters' advantage.
5 The Marines Stopped Jack From Liberating Doflamingo
The Beast Pirates would not allow Doflamingo's capture so easily. They needed him to continue S.M.I.L.E fruit operations, so Jack attacked the Marines' escort ship in hopes of saving him. However, Jack significantly underestimated what the World Government was capable of.
Since former Fleet Admiral Sengoku and Fujitora were both on board, they had a staggering advantage in both strength and raw experience. In the end, Jack was forced to retreat from the battle empty-handed and completely humiliated. The Marines finished their voyage to Impel Down without damage to show for the attack.
4 Aokiji Defeated The Straw Hats By Himself
Aokiji interrupted the Straw Hats shortly after their victory over the Foxy Pirates. Icy and indomitable, he defeated Luffy with ease and left the remaining crew at his mercy. At the time, Aokiji could have easily killed most and captured those the World Government had instructed him
However, he spared Luffy by citing his debt to a friend, though let him off with a warning that Robin would only be trouble going forward. Aokiji's show of strength illustrated how unprepared the heroes were for the New World and foreshowed future disasters.
3 Kizaru Defeated & Captured Arlong
Arlong hoped to stir the Sun Pirates into a frenzy and to encourage conflict between fish-men and humans. Although tearing through the Marines' ranks effortlessly, he was suddenly halted upon Kizaru's arrival.
The Admiral defeated him in a single attack, with his logia providing total immunity from Arlong's attacks. He imprisoned Arlong just as quickly, which staunched the Sun Pirates' appetite for destruction as well as Arlong's own ambitions. It took Jimbei becoming a Warlord for him to be emancipated from Impel Down.
2 Kizaru Crushed The Worst Generation At Sabaody Archipelago
After Luffy punched Charloss, the Marines' full might bore down on Sabaody Archipelago. Kizaru spearheaded the charge, effortlessly defeating the entire Worst Generation and forcing them on the run. However, Kizaru didn't stop there. He also attacked the Straw Hats and would have either captured or killed them if not for Rayleigh's unexpected intervention.
Despite being Roger's second-in-command, he could only hold Kizaru off while the heroes fought Kuma. In the end, the Straw Hats were scattered, broken, and humiliated from battle, allowing the Marines two full years of unmitigated peace.
1 Akainu Murdered Ace In The Battle For Marineford
Drastically outnumbering the Whitebeard Pirates, the World Government was already at an advantage during the battle for Marineford. Just when it seemed as if Ace would escape, Akainu taunted him into rejoining the battle and fought against him personally.
When Akainu saw that Luffy was vulnerable, he attacked him, thereby forcing Ace's intervention. His lava punched through the hero's chest, almost immediately killing him in front of Luffy. It meant that Whitebeard died in vain and forced Luffy to grow considerably before resuming his quest to become Pirate King.