The “Yellowstone” prequel series “1923” at Paramount+ has cast Joseph Mawle, Variety has learned exclusively.

Mawle joins a stacked cast that includes Helen Mirren, Harrison Ford, Robert Patrick, Jennifer Ehle, Jerome Flynn, James Badge Dale, Sebastian Roché, Darren Mann, Michelle Randolph, Marley Shelton, Brian Geraghty, and Aminah Nieves.

Like “1883” before it, “1923” tells the story of a previous generation of the Dutton family as they work to establish the ranching empire featured in “Yellowstone.” Mawle will star as Captain Shipley, described as “the captain of a British cargo ship, who has seen a lot during his years at sea.”

Mawle is best known to TV audiences for his role as Benjen Stark in the megahit HBO series “Game of Thrones.” He also recently starred in the first season of “The Lord of the Rings: The Rings of Power,” but exited the series ahead of Season 2. His film credits include “In the Heart of the Sea,” “Kill Your Friends,” “Half of a Yellow Sun,” and “The Hallow.”

He is repped by Markham, Froggatt and Irwin, and Anonymous Content.

“1923” will premiere on Paramount+ on Dec. 18. Taylor Sheridan created the series and serves as executive producer along with John Linson, Art Linson, David C. Glasser, Ron Burkle, David Hutkin, Bob Yari and Ben Richardson. The series is produced by MTV Entertainment Studios, 101 Studios, and Bosque Ranch Productions.

The premiere of “1923” will debut the same day “Yellowstone” drops its Season 5 midseason finale on Paramount Network. It was previously announced that Season 5 of the mothership series would be split into two installments of seven episodes each. The Season 5 premiere scored a substantial rise in viewership over the Season 4 premiere, notching 8.8 million viewers on Paramount Network alone.