VMBM
And it didn't even bring me down
Czechoslovakia: Probably one of the times they beat the Soviets in the World Championships. I consider Czechoslovakia's history separate from both the Czech Republic and Slovakia's history because then it becomes difficult to tell which accomplishment belongs to which country as opposed to the Soviet Union/ Russia where it is clear that Russia is the successor to the Soviet Union.
Well, until the late 1970s/1980s, nearly all of the best Czechoslovak players were Czechs, with only a few Slovak players (especially stars), like Jozef Golonka and Vladimir Dzurilla, on the team. So, Czechoslovakia's greatest accomplishments mostly happened thanks to Czech players, but then again, probably the Czech Republic can't take all credit for them.