The Acromantula War was a vicious, bloody, and almost entirely unnoticed conflict that erupted between factions of the colony of Acromantula that lived in the Forbidden Forest on the campus of Hogwarts School of Witchcraft and Wizardry.
After the death of Aragog and the Battle of Hogwarts, the colony was left decimated and leaderless, breaking into smaller groups that staked out various tracts of the Forest. Over time, various groups attempted to retake control of larger areas of the Forest, leading to territorial battles that escalated into full-scale war over the Summer of 2011.