For the sake of ruling over one city, Abimelech shed a lot of blood, starting with all 70 of his brothers, bar the youngest, Jotham, who had managed to escape.
Jotham warned Schechem about what they had done:
Judges 9:14-15 Then all the trees finally turned to the thornbush and said,‘Come, you be our king!’And the thornbush replied to the trees, ‘If you truly want to make me your king, come and take shelter in my shade. If not, let fire come out from me and devour the cedars of Lebanon.’
It lasted only three years before the entire city of Shechem suffered the same fate as Abimelech’s brothers. In fulfillment of Jotham’s warning, Abimelech killed all Shechem’s leaders and burnt the city to the ground.