When did the fourth season of "Downton Abbey" air?

The eight episodes comprising the fourth season of "Downton Abbey" aired in the United States on PBS from Jan. 5 to Feb. 23, 2015. The sixth and final season of this series is scheduled to begin on Jan. 3, 2016 on PBS.

"Downton Abbey" is a British television drama which premiered in Great Britain in 2010 and in the United States in 2011. It is set on the fictional Yorkshire Estate beginning in the year 1912 and centers around the wealthy Crawley family and their servants.

Season four begins six months after the death of the character Matthew Crawley, who left behind his young wife Mary and their newborn son. Mary has to rise above her grief to manage Matthew's estate for their child.