Complex sentence: On 9 February 1659, she married Walter Scott of Highchester (herself only 11 years old at the time and her husband, 14), who was created Earl of Tarras a year later.
Split into simpler sentences: On 9 February 1659, aged only eleven years old, she married Walter Scott of Highchester, Who was at that time fourteen. He was created Earl of Tarras a year later.