B-1B Lancers assigned to the 37th Bomb Squadron and 34th Bomb Squadron at Ellsworth Air Force Base, S.D., team up for a training mission April 12, 2017. This year marks the 100th anniversary of the squadrons whose heritage includes being two of the squadrons that participated in the historic Doolittle Raid in 1942. (Photo provided by Ted Carlson, Fotodynamics)