Writing on the Den of Geek web site, Kirsten Howard relates how the forthcoming auction of the late actor David Prowse's personal script for "The Empire Strikes Back" demonstrates the length that producer George Lucas went to in order to preserve the legendary surprise ending regarding the relationship between Darth Vader and Luke Skywalker. While Prowse was hired to physically play Vader, Lucas always intended to have his voice dubbed in the final cut by James Earl Jones. Prowse was unaware of this during filming. The script copy he used did not have the famous shock revelation that Vader was Luke's father. Even Mark Hamill, who played Luke, was unaware of this shocker right up until the pivotal scene was being filmed, though director Irvin Kershner was in on the secret. The scripts had omitted the revelatory line entirely. These tactics caused hard feelings between Prowse and Lucas, as Prowse had felt deceived that it had been decided all along not to use his voice in the final cut. However, few would argue that the gravitas of Jones's instantly recognizable voice added far greater impact to character of Darth Vader. For more, click here.