National Geographic Channel HDTV (NGCHD)

Season 4 takes off with a study of the Luftwaffe, Hitler's air force. (Repeat).

When defeat was inevitable, the Propaganda Machine was used by the Nazis to motivate civilians to fight. (Repeat).

The Nazis' occupation and fortification of Norway is spotlighted. (Repeat).

In Port Protection, tools aren't always used for what they're intended. (Repeat).

Curly helps in fighting some deadly trees on his neighbor's property. (Repeat).

As Mother Nature tries to take back the land, residents work to ensure the community's safety and success. (Repeat).

(Repeat).

In this enhanced episode, Oliver brings in a haul with new fishing pots. (Repeat).

Milestone achievements are only possible with steep challenges in Port Protection. Carl and Matt pull a three-thousand-gallon barrel up a cliff. (Repeat).

(Repeat).

(Repeat).

Milestone achievements are only possible with steep challenges in Port Protection. Carl and Matt pull a three-thousand-gallon barrel up a cliff. (Repeat).

(Repeat).

(Repeat).

A look at how Hitler's vast network of railways became the lifeblood of the Nazi empire, spreading Hitler's ambition and control across Europe and beyond. (Repeat).

A look at how Hitler and Holocaust leader Heinrich Himmler used a vast rail network to transport Jews to their death. (Repeat).

The story of Hitler's Italian Fortress. (Repeat).

Season 4 takes off with a study of the Luftwaffe, Hitler's air force. (Repeat).

Paid Programming. (Repeat).

Paid Programming. (Repeat).

Paid Programming. (Repeat).

Paid Programming. (Repeat).

Paid Programming. (Repeat).

Paid Programming. (Repeat).

In the '70s, John Gotti fights to become boss; in the '80s Whitey Bulger terrorizes Boston. (Repeat).

One drug lord created Mexico's first narco army, unleashing a cartel feared by all. (Repeat).

Meth kingpin Nazario Moreno turns a drug cartel into Mexico's first narco cult. (Repeat).

Pablo Escobar is spotlighted. (Repeat).

Two Chicago women and their drug-dealing husbands helped bring down El Chapo. (Repeat).

Interviews reveal how criminals pioneered the cocaine business in the '70s and early '80s. (Repeat).

AMO hunts for a boatload of coke. CBP finds a hidden body in a trunk. (Repeat).

HSI conducts an undercover drug sting; CBP discovers cocaine in the Rio Grande Valley. (Repeat).

CBP's K9 detects hidden cash. HSI intercepts a two-million-dollar drug trade. (Repeat).

Meth and fentanyl are discovered during an HSI stakeout, while CBP intercepts a shipment of cash and cocaine. (Repeat).

JFK's CBP and HSI in San Diego face a crisis on fentanyl. (Repeat).