In "Order of the Phoenix", ten of Voldemort's most dangerous and loyal followers escaped, including Bellatrix Lestrange. Dumbledore was always vocal in declaring that it was a mistake to guard Voldemort's greatest supporters with Dementors, who have the most to gain if Voldemort returned to power. He is proven right, as the Dementors leave their posts at Azkaban and join ranks with Voldemort. The prison is still in use, but greatly weakened by the revolt of its most effective wardens. Azkaban also had various wizard guards, who kept the Dementors mostly in check and managed the rare prison visits. By the start of "Deathly Hallows", there had been another mass break-out of Death Eaters from Azkaban. Upon Voldemort's takeover of the Ministry, many political prisoners are sent to Azkaban by Ministry traitor Dolores Umbridge, including Xenophilius Lovegood and Muggle-borns persecuted under Voldemort's implementation of anti-Muggle legislation. Such victims are released following Voldemort's downfall, and Umbridge is imprisoned there, along with whichever Death Eaters survived the Battle of Hogwarts.