Complex sentence: Norham, Alnwick and Wark were captured by David I of Scotland in the wars of Stephen's reign, and in 1290 it was at Norham Castle that Edward I decided the question of the Scottish succession in favor of John Baliol.
Split into simpler sentences: Norham, Alnwick and Wark were captured by David I of Scotland in the wars of Stephen's reign. In 1290, it was at Norham Castle that Edward I decided the question of the Scottish succession in favor of John Baliol.