Marines

The Marines are the World Government's military sea force, tasked with law enforcement, international security and military operations. The Marines are one of the Three Great Powers, alongside the Seven Warlords of the Sea and the Four Emperors.

They are present in all the seas around the world, as evidenced by their branch offices. The focus of their assets is on the far more dangerous Grand Line.

In the aftermath of the Battle of Marineford, the base of operations for Marine Headquarters has since been relocated to the New World.

Duties
The duty of the Marines is to maintain a law and order throughout the world and impose the will and might of the World Government. They are therefore considered the key strategic development force in the World Government and are expected to obey its orders at will. Sometimes these orders are questionable, however they are expected to carry them out regardless of opinion. Amongst their duties is awarding bounty hunters the bounties on the heads of a criminal. They tolerate bounty hunters as a method of making their job easier but are known to go out bounty hunting themselves. Apprehended criminals who are brought in alive are handed over to be made an example of, the Marines are left to ensuring the exportation of these criminals to prison and/or to their execution.

Marines often work in pairs with one superior officer and a second in command or a subordinate who is of a lower rank. These partnerships may remain even during promotions with both pairs advancing in rank together. In the pair, the higher ranked officer will give the orders to those under their command, while the other acts as an adviser or information gatherer while ensuring their partner's command is undertaken by the men.

Higher ranked Marines (admirals and the fleet admiral) are expected to be on call to lead the Marine forces into war. This may take form of apprehending many criminals at once, protecting the World Nobles or calling a Buster Call to tackle a situation. Vice admirals are the ones who serve on the ships that the admirals call out and are tasked with carrying out the admirals orders exactly.

The main purpose of the Marines remain footed in the idea of bringing justice to any criminal. They use justice as their constituted policy to manage a world that is made entirely of one ocean much easier. However, the main problem within the Marines is the approach to Justice. They are generally divided between those who support Moral Justice and those who support Absolute Justice with the latter being the code of conduct for the Marines as a central doctrine. Nevertheless, there is little worry from the higher ranked Marines as to how the Justice is carried out so long as it is, leading those who truly support absolute justice to make questionable actions in carrying out their duties.

The Marines are also aided by the Seven Warlords of the Sea in terms of maintaining the "Three Great Powers", and as such, are expected to cooperate when necessary. Despite this, several Marines, such as Aokiji, Akainu, Smoker, Sengoku, Kizaru, and Fujitora think of the Seven Warlords of the Sea as no more than pirates. In turn, the Seven Warlords of the Sea have no obligations to obey the Marines unless under the direct orders of the World Government itself.

One of the most questionable parts of their "Justice" is when it comes to slavery. Despite the practice supposedly being abolished years before, it is often shown that they just look the other way. Especially when it comes to the World Nobles' slaves, where it is even seen as a crime to free said slaves even if the person is merely a child. Often they are tasked to find and retrieve the person to be a slave once again.

The New Age
Thanks to Blackbeard and the death of Whitebeard, a new age has begun upon the world and the "Age of Pirates" that Roger established has ended. Thus began a new time for Marines as well. With the greatest Marines, Sengoku and Garp resigning, a power vacuum for the position of fleet admiral occurred. Despite Sengoku's recommendation for Aokiji to take his position, the other higher echelons wanted Akainu to become fleet admiral. The two admirals commenced a ten day battle on the Punk Hazard island while the details of the battle were agreed to be kept secret. Akainu managed to win and therefore became the new leader of the Marines. However, after the battle, Akainu kept his rival alive. Aokiji, disliking Akainu and his methods, and not wanting to serve under him, resigned from the Marines and disappeared. To compensate the loss of so much military power, the World Government granted the Marines unprecedented power, and with Sakazuki, as the new fleet admiral, the organization has become a much more powerful organization of justice ever since.

Rank System
The system of military rank in place for the Marines is fairly straightforward, where each rank is clearly delineated.

Officers and recruits present at Marine Headquarters are considered "Super-elites". All ranks present from "Lieutenant" above are usually trained here, exceptions being those in command of other Marine bases which includes Axe-Hand Morgan and Nezumi.

Rank Insignia
The Marines do not have a system of rank insignia per se. There is significant variation in the kind of uniform worn by officers, with many opting to wear a variety of dress showcasing their own eccentric style. Marines are also allowed to wield whatever weapon they are most comfortable with, no matter how unusual it is. They are even free to fight bare-handed. However, as a general rule set down by the author, uniform guidelines are as follows: There are, of course, exceptions: Jango and Fullbody wear their own clothes with the "MARINE" hat, despite holding the rank of "Seaman Recruit". This may have something to do with the exceptional circumstances by which both of these men were brought into their present situation, the lenience on the part of their Captain, Hina, or just the fact that the rule is not strictly enforced. Also, G-5 low-rank subordinates do not wear the full uniform due to their disregard of the rules, to the point of wearing slacks and a bucket for a hat.
 * Upon first entering the Marines, new recruits are given the standard uniform, consisting of a white short-sleeved shirt emblazoned with the Marine emblem, a simplified seagull with "MARINE" underneath it, on the back; a blue neckerchief; dark blue trousers; and a baseball cap with "MARINE" across the front. All officers at the rank of Seaman and below wear this. The quasi-rank of "Zatsuyō" adds the kanji 雑 Zatsu ("various" or "odds and ends") to the sleeves, and to the Marine emblem on the back.
 * Once an officer has reached the rank of Petty Officer, he or she can choose from a number of different uniforms, including his or her personal clothes. Only those who really want to appear "sailor-like" will stay with a more traditional uniform. This uniform is generally the standard sailor outfit with red and blue epaulettes.
 * Sailors at the rank of Ensign and above are allowed to wear the coat with "Justice" on the back. This coat tends to be worn like a cape, draped over the shoulders with the arms not in the sleeves. It should be noted that the sleeves of these coats are often much longer than the wearers' arms.
 * For the rank of Lieutenant-Commander and above, a suit worn underneath the "Justice" coat is the preferred attire.

Commissioned Marine Officers

 * Fleet Admiral
 * Admiral
 * Vice Admiral
 * Rear Admiral
 * Commodore
 * Captain
 * Commander
 * Lieutenant Commander
 * Lieutenant
 * Lieutenant Junior Grade
 * Ensign

Infantry and Sailor Division

 * Warrant Officer
 * Master Chief Petty Officer
 * Chief Petty Officer
 * Petty Officer
 * Seaman First Class
 * Seaman Apprentice
 * Seaman Recruit
 * Chore Boy

Special Ranks

 * General Inspector
 * Instructor

Military Powers
Although the exact total number of Marines is unknown, it is without a doubt to stand as the mightiest military power in the world of One Piece. The last time there was an assembly of a massive force was during Ace's Execution. The number reported to have assembled was around 100,000 strong foot soldiers, accompanied by 50 Naval Warships, they are protected by their Headquarters Marineford which is one of the strongest Marine Fortresses in the Grand Line, with numerous defense mechanisms, artillery in almost every direction. There are not only humans but Giants as well, later joined were the Mechanized Pacifista as well. They are also aided by most of the dreaded Seven Warlords of the Sea. Then there are the powerhouses the Admirals, then there came numerous Marine officers who are not only strong and effective, but have made their names known and remembered. Then last but not least, possibly the strongest Marines to have lived, Former Fleet Admiral Sengoku and Former Vice Admiral Monkey D. Garp.

It is a force formed all for the sake of defending the ensuring the continuity of enforcing the might of Justice. With the battle against Whitebeard's forces that came to a close, they are victorious, although many have perished as a result. However that did not stop the unending march of the Marines, they have spent most of their time rebuilding their damaged forces. With Whitebeard's final proclamation and new military staff reassignment with Admiral Akainu becoming Fleet Admiral, the Marines have doubled their efforts into cracking down on the new surge of pirates, especially in the New World.

With the way things are progressing, it is most likely that another war will start and the Marines might have to conjure an even greater force to combat what is to come.