Simplify the following text for a Grade 8 native English-speaking person.
Original: In 1749 Grenville married Elizabeth Wyndham ( before 1731-5 December 1769 ) , daughter of Sir William Wyndham , and the grand-daughter of the Duke of Somerset .
Simplified: In 1749 Grenville married Elizabeth Wyndham ( before 1731-5 December 1769 ) , daughter of Sir William Wyndham .