Good Conduct Medal, Marine Corps, no clasp

The Good Conduct Medal is one of the oldest military awards of the United States Armed Forces. The U.S. Navy's variant of the Good Conduct Medal was established in 1869, the Marine Corps version in 1896, the Coast Guard version in 1923, the Army version in 1941, and the Air Force version in 1963; the Air Force Good Conduct Medal was discontinued from February 2006 to February 2009.
The medal is awarded to any active-duty enlisted member of the United States military who completes three consecutive years of "honorable and faithful service". Such service implies that a standard enlistment was completed without any non-judicial punishment, disciplinary infractions, or court martial offenses. If a service member commits an offense, the three-year mark "resets" and a service member must perform an additional three years of service without having to be disciplined, before the Good Conduct may be authorized.
During times of war, the Good Conduct Medal may be awarded for one year of faithful service. The Good Conduct Medal may also be awarded posthumously, to any service member killed in the line of duty.

The Marine Corps Good Conduct Medal was established on 20 July 1896. The medal was originally a ribbon and medal suspended from a clasp bearing the words "U.S. Marine Corps". The clasp was eliminated after 1935 and the medal has remained unchanged in appearance since that time. Since its inception in 1896, the name of the recipient was engraved by hand on the reverse side of the medal until stamping the name on the medal began during World War II (numbered on the rim) and was done completely by 1951.

Prior to 10 December 1945, four years of honorable creditable enlisted service was required in the Marine Corps for award of the Marine Corps Good Conduct Medal. After 10 December 1945, the required period of service was reduced to three years. Since that latter date, members of the Marine Corps must have three consecutive years of honorable and faithful service in order to be eligible for the medal.

In 1953, the Marine Corps adopted bronze and silver 3/16-inch service stars to denote additional awards of the Good Conduct Medal, replacing enlistment bars showing each honorable period of service.