March 13, 1955: Montreal Canadiens right wing Maurice Richard was suspended for the rest of the season after hitting a linesman during an altercation.
NHL President Clarence Campbell made the decision which sparked major riots in Montreal. The francophone citizens felt Richard's suspension was unjustified.
The riots played out on March 17, when Campbell attended a game in Montreal. Just by chance, that day was Saint Patrick's Day.
The riots led to six figures in damage, close to 40 injuries and upwards of 100 arrests.