30 years ago, Roger Clemens made history by striking out 20 Mariners

On April 29, 1986, a 23-year-old hurler by the name of Roger Clemens took the mound at Fenway Park and did something nobody had ever done before: Strike out 20 batters in one game.
Clemens' opponents that evening were the Seattle Mariners -- specifically the following players who probably had no idea what they were in for:
Looking back, this game meant a lot for the narrative surrounding Clemens at the time. After going 16-9 with a 3.88 ERA over his first two seasons with the Sox in 1984 and 1985, Clemens underwent shoulder surgery and was very much a question mark as he looked to earn a long-term place in Boston.
Faced with some uncertainty regarding his future, Clemens' outing that night was simply brilliant. He did allow three hits and one earned run in a game Boston won, 3-1, but that's not really the lasting memory of the night.
Instead, all anyone remembers are images such as this, over and over and over all night long:

For his efforts, Clemens made history as the only pitcher to strike out 20 hitters in a nine-inning game.
It'd happen again in the future, of course, by Clemens himself a decade later during his final year with the Red Sox:

Cubs rookie Kerry Wood is the only non-Clemens pitcher credited with a 20-strikeout nine-inning game, having done it on May 6, 1998, against the Astros at just 20 years of age. It's still a mystery to most physicists just how Wood managed to get the baseball do to this all afternoon at Wrigley Field, much to Houston's chagrin: 

As for the impact of Clemens' big night in '86, he went on to help the Sox reach the World Series by going 24-4, winning the first of his seven Cy Young awards and being named American League MVP.
So far this season, Phillies right-hander Vince Velasquezhas set the bar for pitchers with a thoroughly impressive 16-strikeout effort against the Padres. Will there be another 20-strikeout game in the future?