Liam served as a Communications Electronics Specialist in the Marine Corps from January 2003 to January 2007. While enlisted he was deployed to Iraq, Kuwait, Thailand, Okinawa, Japan, and Korea. During his last year in the Marines, Sergeant Madden co-founded the Appeal for Redress, a campaign of service members demanding that congress halt the war in Iraq.

Liam is currently serving on the Board of Directors of IVAW. He is a junior attending Northeastern University.