FACEBOOK TOWN HALL Army Gen. Martin E. Dempsey, chairman of the Joint Chiefs of Staff, sits at his desk in the Pentagon, June 24, 2015, preparing for a Facebook town hall. The chairman holds periodic chats with the military world at large via social media. His first was in December 2013. SHARE: Download: Full Size (0.05 MB) Credit: VIRIN: 052865-F-YCS64-165.jpg Photo Gallery