For those who, like me, have a bit of time to kill, know the story and are cool enough to be clued up on the ins and outs of Middle Earth.

What I want to know IS, how come when Sauron had the one ring initially, he got his arse kicked by the elves and men?

This isn't my main question, though: they say in the Fellowship that if he gets it back again, he'll COVER THE LAND IN DARKNESS and it will be the end of time.

Why didn't his having the ring in the first place cause the end of the world like its going to in LOTR?