Osthryth had such a complicated family life that she could put Shakespeare’s story of Romeo and Juliet to shame. Her father was King Oswiu (or Oswy), ruler of Northumbria between the years 642 and 670. At that time, the Northumbrians had a bitter feud with the Mercians—Oswiu only became king of Northumbria after his brother, King Oswald (r. 634-642), was slain and dismembered by King Penda of Mercia. Oswiu avenged his brother by killing King Penda during the Battle of Winwaed, which occurred in 655. After Penda’s death, Oswiu occupied a portion of Mercia and let the rest remain ruled by a puppet ruler. The puppet, interestingly enough, was a man named Peada, who happened to be a son of Penda.
Despite the wars between Northumbria and Mercia, King Oswiu actively tried to strengthen the bond between the rival countries through marriage. He arranged for at least two of his known daughters to marry sons of King Penda. The puppet ruler of Mercia, Peada, was married to Oswiu’s daughter, Alhflæd. The late king Penda’s youngest son, Æthelred, was married to Osthryth, who was mentioned earlier. Penda had another son, named Wulfhere, who did not marry a Northumbrian princess, but instead wed a woman from Kent.
As Osthryth was married to Æthelred, the youngest son of Penda, both wife and husband likely presumed that they would never sit upon the throne during their lives. As such, the couple followed the path taken by most royal family members that had little to inherit—they devoted their time to the church. Nevertheless, the course of events would take some unexpected turns.
