In this clip from episode 4 of NatGeo's "Chain of Command" documentary series, Captain Mark G. Zwirgzdas reflects on his time with Gator Company, 2nd Battalion, 325th Airborne Infantry Regiment as there's a change of command. | Military.com

Set your DVR! #ChainOfCommand premieres Tonight at 9/8c. | National Geographic TV | Facebook

108K views · 199 reactions | From inside the Pentagon to the front lines, gain unprecedented access to the war of our generation in Chain of Command, coming in 2018. | National Geographic TV | Facebook

11K views · 142 reactions | In tonight's premiere of Chain of Command, watch exclusive, striking glimpses of how the war of our generation is being waged, and how it might be won. 10pm HKT, 9pm BKK/JKT on National Geographic #ChainofCommand | National Geographic Asia | Facebook

Colonel Patrick Work starts every day by checking in with his teams fighting ISIS in Mosul. #ChainOfCommand | National Geographic TV