Before Lucas was able to put the "Episode IV - A New Hope" title onto the first Star Wars movie, the very first thing that the movie showed us, after the main title and the "a long time ago..." part, was this line from the crawl:
It is a period of civil war. Rebel spaceships, striking from a hidden base,
have won their first victory against the evil Galactic Empire.
So the first thing this story tells us is that we're in a period of civil war, and it involves the Rebellion and the Galactic Empire. By its very mention of it being "a period of civil war", the movie is telling us that this is unusual in that universe's recent history, yet Episodes II and III both deal chiefly with a civil war, where the Galactic Republic (who becomes the Empire in III) is going through a civil war with the Confederacy of Independent Systems, knownalso as the Separatists. This prequel civil war lasts about 2 years in the saga timeline and embroils nearly the entire galaxy in some way, it's a pretty major event which takes place only about 20 years prior to Episode IV, and in fact seems to be a bigger civil war than the one which Ep 4 speaks of in its crawl. That doesn't make much sense though, the galaxy was largely suffering a civil yet this much more minor insurrection by the Rebel Alliance is called "a period of civil war" where that is only referred to as "the clone wars"? Thoughsome I'm sure will claim I'm just quibbling over semantics, I would reply that this is part of the core of the original Star Wars story andI don't think the prequels make sense this way, I just don't think it fits.