McClung was commissioned an officer in the Marine Corps in 1995 and served on active duty until 2004, when she entered the Reserves. In 2004, she joined Kellogg, Brown, and Root, an American engineering and construction company and went to Iraq as a private contractor. In 2006, she returned to active duty with the Marines and in January 2006, she was deployed to Iraq as a public affairs officer with the I Marine Expeditionary Force. She was promoted to the rank of Major in June. In December 2006, she was in the final month of a year-long deployment to Iraq. On December 6, 2006, McClung was serving with the I Marine Expeditionary Force as the Marine Corps head of public affairs for Al Anbar Province, in charge of embedded journalists. Earlier in the day, she had been accompanying Oliver North with his Fox News camera crew in Ramadi. She subsequently was escorting Newsweek journalists into downtown Ramadi. A massive improvised explosive device destroyed McClung's Humvee, instantly killing McClung and the other two occupants, Army Capt. Travis Patriquin and Army Spec. Vincent Pomante III. The Newsweek journalists were not injured. McClung was the first female Marine officer to be killed in the Iraq war, as well as the first female graduate of the United States Naval Academy to be killed in action since the school was founded in 1845. Major Megan McClung was buried with full military honors in Arlington National Cemetery on December 19, 2006.
Athletic endeavors
While in high school and college, McClung competed as a gymnast. McClung was a triathlete and a marathoner. In October 2006, she organized and ran in the Marine Corps Marathon's satellite competition, Marine Corps Marathon Forward in Iraq.
Posthumous honors
McClung was posthumously honored at Boston University's Metropolitan College 2007 commencement ceremonies with the 2006 “Excellence in Graduate Study in Criminal Justice”, which was presented by Dr. Daniel LeClair. The second annual Major McClung Memorial Run was held August 23, 2008 at Naval Air Station Whidbey Island to raise money for wounded Marines and their families. Marine LtGen Carol Mutter honored Major McClung for her sacrifice during a speech at the Republican National Convention on September 4, 2008. In 2008, the first Major Megan M. McClung Memorial Scholarship will be awarded to a college student by her parents, Drs. Re and Michael and the Women Marines Association. In 2010, The Major Megan McClung Memorial Scholarship Fund was established at her alma mater, Admiral Farragut Academy, and provides need-based financial aid to a deserving female cadet. In Iraq, Army General Ray Odierno was responsible for building a state of the art broadcast studio, which allowed live interviews as well as numerous press events, and he dedicated the studio to Major McClung. The Defense Information School, the United States Department of Defense's training school for photojournalists and other public affairs personnel, presents the Maj. Megan McClung Leadership Award to one graduating member of each Public Affairs Qualification Course.