The reasons behind the war was complex. Both houses clamied to have the right to the English throne as desendents of King Edward III, It didnt help that the current King, Henry VI was mentally sick.
Richard III was the brother of Edward IV and he took throne or was king for only two years before he got killed in the Battle of Bosworth Field.
During the battle, Richard III made a charge for Henry. His horse got stuck in a marsh, so Richard started fighting on foot. He fought bravely, but was killed with an axe to the head. Richard’s crown was found in a bush, and Henry Tudor was crowned on the battlefield, Henry VII.