I wasnt aware of the bad blood, but was recently made aware that Iowa and Illinois didn't play each other for 15 years!

From Wikipedia on Iowa Coach Forest Evashevski

The following week against Illinois, a very physical game turned dirty in the fourth quarter. More than one brawl cleared both benches, and players from both sides were ejected from the game. Evashevski stormed on to the field to protest a call, which fired up the Iowa crowd. When an official tried to mark off an Illinois penalty against Iowa, the Hawkeye crowd started throwing apple cores at the officials. After the game, as the Illinois team was trying to leave the field, an Illinois player got into an argument with an Iowa student and punched him, breaking his jaw. Several Illinois players and ten Iowa players were hurt during the game, with four being sent to the hospital. This incident led to a suspension of the Iowa–Illinois series for 15 years.

That was the foreshadowing of the Jimmy Collins/Bruce Pearl incident many years later.