Millo must have been a fortified place close to, but separate from, Shechem, and perhaps the same as the tower of Shechem mentioned in Judges 9:46-47. The building or enlarging of the better-known Millo, at Jerusalem was one of Solomon’s great works 1 Kings 9:15, 1 Kings 9:24. The population dwelling in Millo though perhaps numerically small, had great weight from possessing the stronghold. Their giving Abimelech the title of king indicates the strong Canaanite influence at Shechem. All the Canaanite chiefs were called kings, but it was a title hitherto unknown in Israel. This title had not been named by those Israelites who offered to make Gideon their hereditary ruler Judges 8:22-23.
The plain of the pillar ... - Rather “the oak of the garrison which is in Shechem.” The oak in question was probably called the “garrison oak,” from a garrison being stationed near it.