The 1969 loss to Michigan initiated what came to be known as "The Ten Year War", in which the rivalry, which pitted some of OSU's and UM's strongest teams ever, rose to the uppermost level of all sports and the competition between Schembechler and Hayes became legendary. Four times between 1970 and 1975, Ohio State and Michigan were both ranked in the top five of the AP Poll before their matchup. The Wolverines entered every game during those years undefeated and won only once, a 10–7 victory in Ann Arbor on November 20, 1971.