When Catherine Kaptain turned on the evening news and saw her son John being struck with his own shoe in a fight with the Boston Bruins, her disdain for the sport her family loved never seemed more justified. “I screamed, ‘They’re beating up my babies!’ ” she said.

Thirty years ago, on Dec. 23, 1979, Bruins defenseman Mike Milbury whacked John Kaptain, a Rangers fan from New Jersey, with a shoe during a bizarre altercation in which all but one Bruins player went over the glass and into the stands at Madison Square Garden. The incident, after a 4-3 Bruins victory, resulted in three players being suspended, lawsuits and the installation of higher glass in the arena. It remains one of the most memorable fan-athlete confrontations in sports.

It all unfolded after Phil Esposito of the Rangers smashed his stick on the ice and skated off to the locker room after failing to convert a breakaway in the waning seconds. When the buzzer sounded, Al Secord, Boston’s rugged left wing, decked the Rangers’ Ulf Nilsson.

“I remembered the sucker punch he gave me earlier in the game, so I thought, an eye for an eye, and I suckered him,” Secord said.