In 942 Hywel's cousin Idwal Foel, King of Gwynedd, determined to cast off English overlordship and took up arms against the new English king, Edmund. Idwal and his brother Elisedd were both killed in battle against Edmund's forces. By normal custom Idwal's crown should have passed to his sons, but Hywel intervened. He sent Iago and Ieuaf into exile and established himself as ruler over Gwynedd, which also likely placed him in control of the Kingdom of Powys, which was under the authority of Gwynedd. As such Hywel became king of nearly all of Wales except for Morgannwg and Gwent in the south.