Background:
Abimelech, a son of Gideon (also known as Jerubbaal), emerges as a significant figure in the Book of Judges. His account is primarily found in Judges 9. Gideon, a judge of Israel, had many sons, and Abimelech was born to his concubine in Shechem. After Gideon's death, Abimelech sought to establish himself as a ruler over Israel, specifically targeting the city of Shechem as his power base.

Conspiracy:
Abimelech's rise to power begins with a calculated conspiracy. He approached his mother's relatives in Shechem, leveraging his familial connections to gain support. Abimelech proposed to the leaders of Shechem that it would be better for them to be ruled by one man, himself, rather than by the seventy sons of Gideon. He appealed to their kinship, saying, "Remember that I am your own flesh and blood" (Judges 9:2).

The leaders of Shechem were persuaded by Abimelech's argument and provided him with seventy shekels of silver from the temple of Baal-berith. Abimelech used this silver to hire reckless and worthless men who became his followers (Judges 9:4).

Massacre of Gideon's Sons:
With his band of followers, Abimelech went to his father's house in Ophrah and killed his seventy brothers, the sons of Gideon, on a single stone. This brutal act was intended to eliminate any potential rivals to his claim to leadership. However, Jotham, the youngest son of Gideon, managed to escape and hide (Judges 9:5).

Proclamation as King:
Following the massacre, the leaders of Shechem and the whole house of Millo gathered and proclaimed Abimelech king at the oak of the pillar in Shechem (Judges 9:6). This marked a significant departure from the traditional leadership of judges in Israel, as Abimelech sought to establish a monarchical rule.

Jotham's Parable:
Jotham, the sole surviving son of Gideon, delivered a parable from Mount Gerizim to the people of Shechem. In his parable, he likened the leaders of Shechem to trees seeking a king. The olive tree, fig tree, and vine all refused the offer, but the bramble accepted, warning that if they had acted in good faith, they would find refuge in its shade; otherwise, fire would come from the bramble to consume the cedars of Lebanon (Judges 9:7-15). Jotham's parable served as a prophetic warning against Abimelech's rule.

Reign and Downfall:
Abimelech's reign was marked by treachery and violence. His relationship with the people of Shechem eventually soured, leading to a rebellion against him. Gaal son of Ebed moved into Shechem and incited the people against Abimelech. In response, Abimelech waged a campaign to suppress the rebellion, resulting in the destruction of Shechem and the massacre of its inhabitants (Judges 9:22-45).

Abimelech's downfall came during an attack on the city of Thebez. As he attempted to burn down a tower where the people had taken refuge, a woman dropped an upper millstone on his head, crushing his skull. Mortally wounded, Abimelech called to his armor-bearer to kill him with a sword to avoid the disgrace of being slain by a woman. His armor-bearer complied, and Abimelech died (Judges 9:50-54).

Legacy:
Abimelech's account serves as a cautionary tale about the dangers of ambition, treachery, and the lust for power. His brief and tumultuous reign highlights the instability and moral decline during the period of the judges in Israel. The narrative of Abimelech underscores the consequences of fratricide and the divine retribution that follows acts of injustice and betrayal.