While Offa was an effective leader in Mercia during his life, his dynastic purge was a disaster. Looking at what followed, it appears that he heavily targeted extended members of his own family. Now this placed his immediate family in a very good position to pursue power… and we did see a seamless transfer of power to his son, as well as the placement of his daughters in prestigious positions (both through marriage, and also within the church, which was rapidly becoming an extension of royal power). And actually, the dynastic policies during Offa’s reign were so effective that even Queen Cynethryth (who was quite powerful while her husband was alive) continued to wield considerable power in Mercia after his death. Even managing to take possession of the monastery of Cookham.