The Battle of Witches' Rock was a wizarding battle that occurred in January of 2011. The battle took place between Aurors from the Dinétah Auror Authority (including Henry Tsotsie, along with Alexandra Quick) and a horde of Dementors summoned from the Rock by John Manuelito following his duel with Quick.
According to Tsotsie, the Battle occurred during a larger attack by the Dark Convention in the Indian Territories in which Dark Wizards attempted to summon Dementors from Orange Rock as well. Manuelito had intended for the Auror Authority to be preoccupied with a roving pack of werewolves that he had been released by him and his conspirators near the town of Little Creek, thus leaving the Auror Authority incapable of dealing with the Dementor attack.
Quick had lured the werewolf pack toward Witches' Rock, however, and prevented Manuelito from performing his full ritual at the Rock's summit, lessening the damage of the Convention's full attack and focusing the fighting at the Battle of Witches' Rock.