Culture of the United States Marine Corps
Two styles of swords are worn by Marines. The Marine Corps officers' sword is a Mameluke Sword, similar to the Persian shamshir presented to Lt. Presley O'Bannon after the Battle of Derna during the First Barbary War. After its adoption in 1825 and initial distribution in 1826, Mameluke Swords have been worn by Marine officers ever since, except during the period 1859–1875, when they were required to wear the Army's Model 1850-foot officers' sword. Upon returning to the traditional sword, many officers gave their Army swords to their senior noncommissioned officer, creating the basis for the NCO sword. Generally, Marines are the only branch where enlisted members regularly carry a sword (the Army authorizes platoon and first sergeants to carry a Model 1840 sword during some ceremonies, while the Chief of Naval Operations authorized Chief Petty Officers and above to carry an optional ceremonial cutlass with dress uniforms in 2010).
M4 carbine
By July 2015, major Marine Corps commands were endorsing switching to the M4 over the M16A4 as the standard infantry rifle, just as the Army had done. This is because of the carbine's lighter weight, compact length, and ability to address modern combat situations that happen mostly within close quarters; if a squad needs to engage at longer ranges, the M27 IAR can be used as a designated marksman rifle. Approval of the change would move the M16 to support personnel, while armories already had the 17,000 M4s in the inventory needed to outfit all infantrymen who needed one. In October 2015, Commandant Robert Neller formally approved of making the M4 carbine the primary weapon for all infantry battalions, security forces, and supporting schools in the U.S. Marine Corps. The switch was to begin in early 2016 and be completed by September 2016. In December 2017, the Marine Corps revealed a decision to equip every Marine in an infantry squad with the M27, replacing the M4 in that part of the service. MARSOC will retain the M4, as its shorter barrel is more suited to how they operate in confined spaces.