'Chain of Command' - Capt. Mark Zwirgzdas' Change of Command

The National Geographic Channel continues its ambitious, eight-part documentary series "Chain of Command" on Monday January 29nd at 9pm ET with episode 4, "The End of the Beginning."

The show aims to examine the war on extremism from as many perspectives as possible.In every facet of the war on extremism there is the recognition of how long the fight will take. In Mosul, the battle may be nearly won, but ISIS is still recruiting foreign fighters from far and wide, including the unlikely setting of Trinidad and Tobago, where Muslim leaders are the tip of the spear in the fight. The spread of ISIS ideology is a reminder that this is just the end of the beginning of the war.

We've got a clip from this week's episode. Captain Mark Zwirgzdas reflects on his time in Iraq and prepares for a change of command in Gator Company, 2nd Battalion, 325th Airborne Infantry Regiment.