Master-at-arms

United States Navy master-at-arms
Master-at-arms badge
Active	1797 – Present (August 1st official birth date as per BUPERSNOTE 1440 CH-1 of 1973)
Country	United States of America
Allegiance	Constitution of the United States of America
Branch	United States Navy
Type	Naval Security Force
Size	8,000+ master-at-arms
Part of	U.S. Department of the Navy
Garrison/HQ	United States Fleet Forces Command, Norfolk, VA
Colors	Blue, Gold
Engagements	American Revolutionary War Barbary War American Civil War Spanish–American War World War I World War II Korean War Vietnam War Persian Gulf War Kosovo War Operation Enduring Freedom Operation Iraqi Freedom Operation Neptune Spear
Commanders
Commander, United States Fleet Forces Command	Admiral Bill Gortney

Master-at-Arms
Rating insignia
Issued by	United States Navy
Type	Enlisted rating
Abbreviation	MA
Specialty	Law enforcement

A master-at-arms (US: MA; UK: & Pakistan MAA) may be a naval rating, responsible for law enforcement, regulating duties, security and force protection; an army officer responsible for physical training; or a member of the crew of a merchant ship (usually a passenger vessel) responsible for security and law enforcement. In some navies, a "ship's corporal" is a position—not the rank—of a petty officer who assists the master-at-arms in his various duties.

The master-at-arms (MAA) is a ship's senior rating, normally carrying the rank of chief petty officer or warrant officer. He or she is in charge of discipline aboard ship, assisted by regulators of the Royal Navy Police, of which he is himself a member. The non-substantive (trade) badge of an MAA is a crown within a wreath.

The post of master-at-arms was introduced to the Royal Navy during the reign of King Charles I; their original duties were to be responsible for the ship's small arms and edged weapons, and to drill the ship's company in their use. This was not an onerous task, and masters-at-arms came to be made responsible for "regulating duties"; their role as weapons instructors was eventually taken over by the chief gunner.

The MAA is addressed as "Master" if holding the rank of chief petty officer, regardless of gender, and is often nicknamed the "jaunty", a corruption of the French gendarme, or the "joss/jossman".

As a result of the Armed Forces Act 2006, the term Regulating Branch was changed to Service Police and the branch title changed to the Royal Navy Police and reported to their respective service's Provost Marshal, who was responsible to the First Sea Lord.

In the British Army, a master-at-arms is a commissioned officer of the Royal Army Physical Training Corps, posted as an SO2 or SO3 at Divisional HQ or higher command, and responsible for overseeing all fitness training in subordinate units. The role is filled by RAPTC WO1s at Brigade HQs, while WO2s or staff sergeant PTIs are embedded at unit level.