The answer is: Destroyed the rest of the royal family

2 Ki 11:1 - Athaliah who was intent on taking over the kingdom killed all the royal family except for Joash who was hidden away for six years to keep the royal line alive.

Athaliah, the only queen regnant of Judah and a formidable figure in the Bible, is a cautionary tale of power and ambition gone awry. When she learned of her son Ahaziah's death, her immediate response was shocking: she sought to eliminate any competition for the throne by massacring all possible heirs of the royal lineage. That's some intense royal behavior!

Interestingly, Athaliah was the daughter of King Ahab of Israel and Queen Jezebel, two other powerful figures whose stories are laden with conflict and idolatry. Her actions become more troubling, revealing a legacy of ruthless ambition at any cost. Despite her attempts to erase the royal family, one child, Joash, eluded her clutches. This child was hidden for a whopping six years—an epic temporal and geographic struggle in the shadows of the palace. When Joash finally emerged, he was anointed king, leading to Athaliah's dramatic downfall.

On the theme of queens, Athaliah stands out among many women in Scripture who had a significant, albeit sometimes ominous, impact. Unlike figures like Esther or Deborah, who fought for justice and saving their people, Athaliah exemplifies the tragic extremes of power's allure.

You could also view her story as a stark lesson about the risks of ambition interwoven with the complexity of familial loyalty. The drama of her rule spun a deep web in Judah’s history—reminding us just how tangled politics and personal motivations can become!