After the making of Episode IV V and VI of star wars, was it immediately decided to make the 3 prequels or was it due to some other factors (eg: financial)?
George Lucas had the basic outlines for the prequels written, including many characters and settings, even as Return of the Jedi was wrapping.
However, he lost his enthusiasm to continue the series in 1987 following a financially damaging divorce, and turned his attention to other endeavors - the culmination of which would be THX sound, Pixar, advancements in video gaming and pushing the cinematic boundaries through ILM. Eventually though, the Star Wars saga began to gain momentum again due to the comics produced by Dark Horse and the novels written by Timothy Zahn, and when he saw the results of his company's CGI effects in films such as Terminator 2 and Jurassic Park, he realized the technology was available for him to realize his original vision. Also, Lucas could see that the fan-base was growing, rather than dwindling, and as an independent company, Lucasfilm needed to generate its own income in order to finance other projects, and a new Star Wars film (and associated merchandising) would certainly fill the coffers.
He began writing the script for Episode 1 in 1994 (putting a long-gestating project, Red Tails, on hold) and made the focus of the saga the story of Anakin Skywalker which encompassed the classic theme of the rise, fall and redemption of a hero. It is noteworthy that many of the character names and settings from the prequels can be found in the very earliest drafts of the original Star Wars.
Episode IV was not in opening of the original release, it was added for the re-release a few years later. This is one of those we will never know type questions. Lucas has made many claims and who knows what the real story is.
He broke movie making rules when he made this movie, got kicked out of the directors guild if I understand it right. Changed the world from a lot of unhappy ending movies to the heros win at the end with a happy ending. My guess is he was probably happy to have had at least had this project at all. If it failed who cares if there were other stories, if it succeeded then use the money and success to make more movies. From star wars to jedi, the little furry animals were supposed to be wookies, but that would make chewbacca an also-ran not a special character, and other reasons the story was changed. How much time was there from star wars to jedi and from jedi to episode 1? The better question might be how many hundreds of versions of these stories were there before settling in on the 6 we have? There were supposed to be 9, three prequels and three sequels after this set, where are the other three, why waste time messing up star wars every so many years and just finish the series?
The problem with a pre-quel or set of them in this case, esp with a cult classic like star wars, you have to get all the facts right, you have to create darth vader, the empire, luke and leah and so on. episode III is 100% checklist, nothing else, kids born, check, kids distributed, check, create vader, check, empire in place, check, etc etc.
bottom line the Episode IV tag was not part of the original, it was added after the original was a huge success, big enough to have a re-release (this was before vcrs and cable tv with movie channels), we will never know...