During the peak of the War, Voldemort had taken an extreme interest in beasts. He had begun to worry that he wouldn’t be able to garner enough support from the Wizarding World to win a War. So he ventured into the realm of creating soldiers instead. In the beginning, he experimented with breeding, specifically Dragons but the entire process took too long. By the end, he had been using Vampires and Werewolves to change innocent witches and wizards. He would then neglect and abuse the newly changed victims into an almost feral state, releasing them unpredictably into the Muggle public in blatant discard for the Statue of Secrecy. 