Big 2, Little 8: The Golden Years (1969-1980)
From 1969 (Bo's first season) to 1980, U-M won or tied for the Big 10 Championship nine times and appeared in 6 Rose Bowls while OSU won ten titles and appeared in 6 Rose Bowls during that span. Incidentally, during the 1970's U of M had the nation's best regular season record at 96-10-3. This era was dominated by the respective coaches of the two schools: Bo Schembechler for U of M and Woody Hayes of OSU.
The rivalry between the schools (and the two coaches) was so intense during that era that it is commonly referred to as "The Ten Year War". Bo had a 5-4-1 record vs. Woody in U-M/OSU games during that era from 1969-1978. U of M finished 1978 ranked 5th in the nation which was the 10th consecutive year Bo had led U of M to a final top 10 ranking. Although both schools have continued to enjoy considerable success since the "Big 2" domination of the 70's (both schools won National Championships in the past 10 years) I don't think anyone will ever dominate the conference again to the extent these two teams did during the era of 1969-1980. With a decrease in scholarships and a corresponding increase in parity, the talent level of other Big 10 schools is too high to ever be dominated on such a long term basis again. It was nice while it lasted. Go Blue!