Pope John IV
Reigned from 24 December 640 to 12 October 642.
Born in Dalmatia; died in Rome, Italy.
As pope he endeavored to alleviate the distress in his native land caused by the invasion of the Slavs.
He sought to convert the Slavs from the Greek to the Latin Rite.
He condemned the Monothelite heresy, and in a letter to Constantine III, defended the memory of Pope Honorius, who had been falsely accused of favoring the heresy.
The emperor died but his son Constans II continued the assault on the heresy by withdrawing the Ecthesis.
New Catholic Dictionary