| 1st Provisional Marine Brigade | |
|---|---|
 Members of the 1st Provisional Marine Brigade carry a wounded man on a stretcher during the Battle of Pusan Perimeter in 1950. | |
| Active | May–July 1912 14 July 1941 – 25 March 1942 18 April – 9 September 1944 1 June – 1 October 1947 7 July – 13 September 1950 |
| Country |  United States of America |
| Allegiance |  United States Marine Corps |
| Branch | Active duty |
| Type | Marines |
| Role | Amphibious warfare Anti-tank warfare Armoured warfare Artillery observer Cold-weather warfare Combined arms Counter-battery fire Force protection Fire support Indirect fire Jungle warfare Maneuver warfare Military intelligence Military supply-chain management Patrolling Raiding Reconnaissance |
| Size | Brigade |
| Nickname(s) | "Fire Brigade" |
| Engagements | Negro Rebellion |
| Commanders | |
| Notable commanders | John Marston Lemuel C. Shepherd Edward A. Craig |
The 1st Provisional Marine Brigade was a marine brigade of the United States Marine Corps (USMC) that existed periodically from 1912 to 1950. It was an ad hoc unit formed for specific operations and not considered a "permanent" USMC unit.
The brigade saw five brief activations for service over a 40-year span. First created in 1912 for duty in Cuba following the Negro Rebellion, the brigade was not activated again until 1941 when it was hastily constructed from the 6th Marine Regiment to garrison Iceland after British forces occupied the country during World War II. The brigade saw service once more in the war during the Battle of Guam in the Pacific War, conducting an amphibious landing on that island's southern sector and subduing resistance from Japanese forces. It was activated once more in a brief organizational shift after the war.
The brigade was formed again in 1950 when it was hastily assembled for service in the Korean War. The brigade participated in a counterattack at Masan before reinforcing United States Army units during the Battle of Pusan Perimeter, and at the First and Second Battles of Naktong Bulge along the Naktong River. The brigade was deactivated for the last time when it was merged with the 1st Marine Division.