| 2nd Battalion 5th Marines | |
|---|---|
 2/5's insignia | |
| Active | July 1, 1914 – August 13, 1919 May 17, 1921 – January 5, 1929 February 14, 1929 – April 12, 1930 September 1, 1934 – present |
| Country |  United States of America |
| Branch |  United States Marine Corps |
| Type | Infantry battalion |
| Role | Conducts expeditionary, combined-arms, and mechanized operations in order to support theater engagement plans and contingency operations |
| Size | 1,200 |
| Part of | 5th Marine Regiment 1st Marine Division |
| Garrison/HQ | Marine Corps Base Camp Pendleton |
| Nickname(s) | The Bloodline |
| Motto(s) | "Retreat, Hell" |
| Engagements | World War I |
| Commanders | |
| Current commander | Lt.Col Clinton K. Hall |
| Notable commanders | William J. Whaling Harold E. Rosecrans Gordon D. Gayle Lewis W. Walt Ernie Cheatham |
2nd Battalion 5th Marines (2/5 or "Two Five") is an infantry battalion in the United States Marine Corps consisting of approximately 800 marines and sailors. They are based out of Marine Corps Base Camp Pendleton, California and fall under the command of the 5th Marine Regiment and the 1st Marine Division. The battalion has seen combat in World War I, World War II, the Korean War, the Vietnam War and the Gulf War and has deployed many times in support of Operation Iraqi Freedom and the War on Terror.
2/5 is the most highly decorated battalion in the Marine Corps, and their motto, "Retreat, Hell!", comes from the French trenches of World War I, when a Marine officer named Lloyd W. Williams was advised by a French officer to retreat and replied, "Retreat? Hell, we just got here!"