Complex sentence: In 1702 she succeeded to one of her father's titles of Baron Strange and on 21 May 1706, she married the 4th Earl of Anglesey, whereupon Henrietta became Countess of Anglesey.
Split into simpler sentences: In 1702 she succeeded to one of her father's titles, the Barony of Strange. On 21 May 1706, she married the 4th Earl of Anglesey and so became the Countess of Anglesey.