During a military campaign, Vlad the Impaler, the basis for Dracula, once pulled his troops out of a major engagement in a valley at dusk so that the sun was in their enemiesâ eyes. Once they were over the hill, they set loose a bunch of rabid bats who flew away from the sun (towards the enemy) and attacked them, leading to significant infection in their ranks, and Vladâs eventual victory. Because of how the bats appeared from where Vladâs soldiers appeared to be at dusk, myth stated that the soldiers turned into bats at night, which is where the âDracula can change into a batâ thing came from.