Judges 9:6

And all the men of Shechem gathered together
Upon the return of Abimelech, after he with his banditti had committed the execrable murder of his brethren:

and all the house of Millo;
which was either the men of a place near to Shechem, or of his brother's family, or of some grand leading family in Shechem; or it may mean the town hall, where the principal inhabitants met in full house, as Millo signifies, on this occasion:

and went and made Abimelech king;
which was a most bold and daring action; being done without asking counsel of God, without which no king was to be set over Israel, and by a single city, without the knowledge, advice, and consent of the body of the people of Israel: by the plain of the pillar that was in Shechem; the place where they met together, and did this business in voting Abimelech to be king, was near a place where a pillar was set in Shechem; or by the oak of the pillar in Shechem, and so may mean the stone under an oak, which Joshua placed there as a testimony between God and the people, ( Joshua 24:25-27 ) and here, in the same place where Joshua convened the people of Israel, and made his last speech to them, was this business done.