Pictured by an unknown photographer, five U.S. Marine Corps privates with fixed bayonets pose under the command of their noncommissioned officer, who displays his M1859 Marine NCO sword at Navy Yard in Washington, D.C. in April 1864. Marines participated moderately in the Civil War, mostly performing blockade duty. Library of Congress
This illustration depicts the first hoisting of the American flag by U.S. Marines on Cuban soil during the Spanish-American War. Newscom
This illustration, 'American Marines in Belleau Wood,' from 1918 was originally published in the French Magazine 'Illustrations.' Georges Scott (1873-1943)
US Marines don gas masks to combat the Germans' use of poison gas in World War I. Newscom
US Marines played a central role in the Pacific theater of World War II. Here, Marine Raiders gathered in front of a Japanse dugout on Cape Totkina on Bougainville, Solomon Islands, which they helped to take in January 1944. Edisto Images/Newscom
Marine infantrymen take cover behind a tank while it fires on Communist troops during the Korean War on May 22, 1951. Newscom
U.S. Marines move forward after effective close-air support flushes out the enemy from their hillside entrenchments. Billows of smoke rise skyward from the target area outside of Hagaru-ri, Korea on December 26, 1950. Cpl. McDonald/Marine Corp/Newscom
Marines blow up bunkers and tunnels used by the Viet Cong during the Vietnam War on May 5, 1966. National Archives/MCT/Newscom
Marines prepare to fire thier howitzers against possible emeny contact in Iraq, on March 26, 2003. Sgt. Kevin R. Reed/US Marine Corps/Newscom
U.S. soldiers from the 1st Battalion, 155th Brigade Combat Team and Marines from the 2nd Air Naval Gunfire Liaison Company walk back to their Humvees after searching through a field for an insurgent mortar pit in Al Iskandariyah, Iraq, on March 29, 2005. Airman 1st Class Kurt Gibbons III/U.S. Air Force/Newscom
U.S. Marine Corps Sgt. Daniel Leach radios fellow Marines during an operation in the Al Anbar province of Iraq June 11, 2008. Tyler W. Hill/Rapport Press/Newscom
A Marine sits alert in a tank before going into combat, at Camp Dwyer in the south of Helmand Province, southwest of the Afghan capital of Kabul on May 4, 2008. Massoud Hossaini/AFP/Newscom
Troops may express political opinions and are encouraged 'to carry out the obligations of citizenship,' but Marine Sgt. Gary Stein was warned that his Facebook posts crossed a line.
ByAnna Mulrine, Staff writer
The other-than-honorable discharge given to Marine Sgt. Gary Stein for writing “Screw Obama” and other criticisms of the president on Facebook means he will lose all of his military privileges, including access to military health care and education benefits, as well as the right to shop in the tax-free grocery and department stores on base.