Gunnery Sgt. Brian A. Knowles, U.S. Marine Corps Reserve, Centennial Project Historian, has a conversation with an attending guest during the pre-concert reception of Marine Forces Reserve Centennial Celebration at the Conservatorio de Musica de Puerto Rico in San Juan, Puerto Rico, Oct. 18, 2016. The Marine Corps Reserve is commemorating 100 years of rich history, heritage, espirit-de-corps, and a bond with Puerto Rico and communities across the U.S. The celebration recognizes the Reserve's essential role as a crisis response force and expeditionary force in readiness, constantly preparing to augment the active component. (U.S. Marine photo by Master Sgt. John A. Lee, II / Released)