Vincent Kartheiser, Mad Men’s Pete Campbell, plays the English separatist who served as Plymouth Colony’s governor for about 30 years in Nat Geo’s first scripted miniseries Saints & Strangers. He says he had been looking to do a very different role than that he’d played the last seven or eight years.

And, he told TV critics this afternoon at TCA, he knew “Nat Geo would honor and bring historical accuracy” to the story.

On the heels of the record-breaking ratings for Killing Jesus, National Geographic Channel set its next scripted event, greenlighting the four-hour miniseries Saints & Strangers from Bosch co-creator Eric Overmyer, Sony Pictures Television and Little Engine Productions. Nat Geo’s first miniseries, set to debut this Thanksgiving, tells the story of the approximately hundred men, women and children who boarded the Mayflower for a one-way trip to the New World.

Executive producer Gina Matthews said during today’s panel that she and EP Grant Scharbo “are huge fans of Mad Men and, in particular, of Vincent. And Williams Bradford is such a challenging role,” she said of Kartheiser’s character. “He begins the journey not as the leader…What’s incredible is to see Bradford, who he becomes and the trajectory. He ultimately goes to some dark places…but has a moral compass. Vincent has this incredible quality to be both. He has this open quality that draws you in.”

Ron Livingston, who plays the colony’s original governor,  John Carver, told TV critics the “one thing that makes this thing sing is it captures that, from the get-go, the building of the United States of America.” That, he said, involved “people who were at opposite ends of the political spectrum” and were there for “very different reasons” of religion and economic opportunity, and were “thrown together of necessity” but did not get along and, had they stayed in Europe “would not have chosen to associate at all.”