US Marines clear houses, a the site four insurgents staged a bloody counter-attack, killing one Marine and wounding many others, in Fallujah, Iraq, on November 2004. Scott Peterson/The Christian Science Monitor/Getty Images
US Marines sit on their Amphibious Assault Vehicles (AAV) while waiting for a go signal to roll into the water facing the South China Sea during a US-Philippines military exercise, at San Antonio, Zambales, north of Manila in June, 2014. Erik De Castro/Reuters
A US Marine cries during the memorial service for 31 killed US servicemen at Camp Korean Village, near Ar Rutbah, western Iraq, in 2005. Thirty Marines and one sailor died on Jan. 26, 2005 when their helicopter crashed near Rutbah while conducting security operations. Anja Niedringhaus/AP
US Marines respond to a gas attack near Verdun, France, in 1918 during World War One. AP
An MV-22B Osprey, a vertical takeoff and landing tilt-rotor aircraft, flies in view of downtown Seattle in support of Marine Week in July 2014. Elaine Thompson/AP
A US Marine stands behind the American and Marine Corps flags during a ceremony in honor of the Marine Corps' 231st birthday at the Marines headquarters Haditha Dam in Iraq's Al Anbar Province, Iraq, in November 2006. Cpl. Luke Blom/US Marine Corps/AP
US Marine Corps drill instructor yells at a recruit after wakeup attention detail, part of the twelve week training program, in Parris Island, S.C. in January 2005. Shannon Stapleton/Reuters
US Marines training at the Marine Corps Mountain Warfare Training Center in Bridgeport, California, walk on a trail, in 2009, with their packed mules and donkeys carrying water, food, and weapon systems in preparation of traversing some of the most rugged terrain in Afghanistan. Tony Avelar/The Christian Science Monitor
Marine Sgt. Jason Smith kisses the hand of his daughter Isabella, as daughter Hannah looks on, in Fort Worth, Texas, in December 2012 upon his return home from his Mideast overseas deployment to the Naval Air Station Joint Reserve Base. Louis DeLuca/The Dallas Morning News/AP
US Marine Pfc George C. Miller carries a machine gun on his shoulder while his platoon moves forward on a muddy jungle trail, at an unknown island, during the Pacific theater of war operations in World War II. AP
US Marines run through dust kicked up by a Black Hawk helicopter as they rush a colleague wounded in an IED strike for evacuation near Sangin, in the volatile Helmand Province of southern Afghanistan in 2011.
US Marines clear debris from the Breezy Point neighborhood which was left devastated by superstorm Sandy in the New York borough of Queens in November 2012 Adrees Latif/Reuters
US Marine Sgt. Adam Wilson mans a Mark 19 heavy gun at a fire position near Musa Qaleh, in northern Helmand Province, southern Afghanistan in 2010. Kevin Frayer/AP
Marines practice non-lethal crowd control techniques at the Marine Corps base at Camp Pendleton, Calif. in 2012. The Marine Corps has created its first police battalion, which can land within three days at any hot spot on the globe to gather evidence and intelligence to take down criminal networks and do other law enforcement work.
Marines and sailors 'man the rails' aboard the nuclear-powered aircraft carrier USS Enterprise as she approaches the Naval Station in Norfolk in February 2004. Photographer's Mate First Class Shawn Eklund/U.S. Navy/Reuters
Marine recruiters Staff Sgt. Jody Van Doorenmaalen (r.) and Sgt. Andrew Mrozik (l.) talk with high school senior and potential recruit Jeff Gold in 2005, during a visit to H.D. Jacobs High School in Algonquin, Ill. Jeff Roberson/AP
A recruiting poster for the US Marines from 1941. AP
People board a US Marines C-130 aircraft after leaving their homes in the typhoon-battered Tacloban, at Tacloban airport in November 2013. Typhoon Haiyan smashed through the country laying waste to just about everything in its path, and killing more than 4,000 people. Athit Perawongmetha/Reuters
Airstrikes alone will not be enough, Defense Secretary Chuck Hagel said Friday. The fight in Syria against the Islamic State promises to be particularly complex, with a need for as many as 15,000 trained rebel fighters.
ByAnna Mulrine, Staff writer
It will take between 12,000 to 15,000 trained fighters with the moderate rebel forces to begin to recapture territory lost to the Islamic State (IS) in Syria, America’s top military officer warned Friday.