Judges 9:6
And all the men of Shechem gathered together, and all the house of Millo, and went, and made Abimelech king, by the plain of the pillar that was in Shechem. And all the men of Shechem gathered together, and all the house of Millo, and went, and made Abimelech king, by the plain of the pillar that was in Shechem.
After Gideon's death the people forgot the Lord who had delivered them from all their enemies on every side. They showed no kindness to the house of Jerubbaal in return for all the goodness Gideon had shown to Israel. Yet they gathered to make Gideon's base-born son Abimelech king.
To sustain his power Abimelech murdered all but one of Gideon's lawful children. This cruel course toward Gideon's house was the expected result of ingratitude to God. When men cast off the fear of God they soon depart from honor and integrity. Appreciation of the Lord's mercy leads to appreciation of those whom He employs as instruments to bless His people.