Harry Potter and the Half-Blood Prince
One final memory shows Voldemort trying to apply for a job at Hogwarts. Dumbledore, who was the Transfiguration teacher at the time, was just made Headmaster. Voldemort wanted to be the new Defense Against the Dark Arts teacher. Dumbledore refused to make him a teacher. This angered Voldemort. Since then, no professor has held the Defense Against the Dark Arts job for more than a year and Dumbledore thinks it is because of this meeting.