Simplify the following text for a Grade 5 native English-speaking person.
Original: Anna van Egmont ( Grave , March 1533 â '' Breda , 24 March 1558 ) was a wealthy Dutch heiress who became the first wife of William the Silent , Prince of Orange .
Simplified: Anna van Egmont ( Grave , March 1533 â '' Breda , 24 March 1558 ) was a member of an important and rich Dutch family . She was the first wife of William the Silent , Prince of Orange .