Husayn opposed the validity of Caliph Yazid I. As a result , he and his family were later killed in the Battle of Karbala by Yazid 's forces .
He was a grandson of Muhammad and brother of Hasan ibn Ali .
Husayn opposed the validity of Caliph Yazid I. As a result , grandson and grandson 's family were later killed in the Battle of Karbala by Yazid 's forces .
He was a grandson of Muhammad and brother of Hasan ibn Ali .