For those not very familiar with the Star Wars fandom, Obi-Wan and Darth Vader's fight in the first-ever Star Wars movie, A New Hope, might be a bit perplexing. Throughout the fighting scene, Obi-Wan is very calm, and, eventually, he seems to give up, having made peace with his fate. But why did Obi-Wan let Darth Vader kill him?
Why Did Obi-Wan Let Darth Vader Kill Him in Star Wars?
During his lightsaber duel with Darth Vader, Obi-Wan willingly sacrifices himself to allow the rest of the group to escape the Death Star with Leia. At the beginning, he earnestly seemed to try to hold Darth Vader off, but when he made sure that everyone in the group had escaped, and that Luke was safe, he was ready to die.
This, however, doesn't mean that Obi-Wan sacrificed himself because he lost his will to live, nor that he meant to erase himself from the picture.
In what must have been a very emotional battle with his former apprentice, whom he failed to save, Obi-Wan was able to smile and even give the viewers a hint about his reasoning.
During the fight, Obi-Wan told Darth Vader that if he were to strike him down at that point, he would become one with the Force, thus infinitely stronger.
Obi-Wan wasn't afraid of dying as he knew that, if he became one with the Force he would be able to keep communicating with Luke and continue training him.
The last movie of the prequel trilogy reveals that Obi-Wan's own master, Qui-Gon Jinn, had investigated a method to communicate even after his death. It's likely that Obi-Wan followed his master's footsteps and was therefore confident that we would be able to reach out to his apprentice no matter what happened to his mortal body.
More practical reasons for Obi-Wan's sacrifice might be the Jedi master's awareness that, if Luke saw him fight for his life, he would step in to help, at a time when he was not yet ready to face Darth Vader.
Of course, as long as an explicit answer has not been provided, the question of Obi-Wan's sacrifice remains open to speculation. The new Obi-Wan Kenobi series might delve more deeply into Obi-Wan's thought process and plans - especially if he ends up meeting Darth Vader in the show.