After the success of A New Hope, series creator George Lucas surprisingly opted not to return to direct the film's sequel, which would later be called The Empire Strikes Back. He was too busy to direct, he reckoned, and decided that someone else would be better-suited to be director.
To find a suitable director for his film, George Lucas looked to his past and remembered a former teacher from his time at USC Film School called Irvin Kershner. Lucas approached Kershner and offered him the opportunity to direct the film, an offer which Kershner accepted after initially turning the opportunity down out of fear that a sequel could never be as good as the original film. After a call to his agent, however, Kershner quickly relented and accepted Lucas' offer to direct the film.
Because of Lucas' familiarity with Kershner, he gave him a lot of leeway to make changes to the script as he saw fit, which he often did to alter tone and story beats as needed.
Although filming was marred with a number of challenges, Kershner constructed a tremendous film with an eye towards the spectacular and fantastical (which was possible because of the film's large budget).
