U.S. Air Force Capt. Christopher Underwood II, 633rd Air Base Wing chaplain, performs the invocation during the Martin Luther King Jr. Day ceremony at Langley Air Force Base, Va., Jan. 17, 2014. The holiday, which celebrates the sacrifices made by King, is celebrated on the third Monday of January each year. (U.S. Air Force photo by Airman 1st Class Areca T. Wilson/Released)