King is dead. Long live the king.
“Both Stephen and Matilda had children, and this was another important factor in the struggle for the crown. Had either of them been childless it would have weakened their position considerably, because even if they were victorious now they would have no clear successor, and the current situation would only be replicated a few years down the line – something all parties were keen to avoid. “
https://www.historytoday.com/archive/feature/succession-crisis-tore-england-apart