First Duel on Mustafar

The First Duel on Mustafar occured after Anakin Skywalker, now Darth Vader, had slaughtered the last of the Trade Federation. He then saw his wife Padme Amidala land on the docks. He greeted her, but became raged and yelled at her when her ship unknowningly was carrying Obi-Wan Kenobi. Padme went back into the ship and hid.

Duel
Obi-Wan and Anakin got into a short argument then broke out into a duel that went into the control room. Obi-Wan witnessed the corpses of all the Trade Federation Board members that had been killed by Anakin, with the exception of Nute Gunray's corpse on the landing platform. The fight went onto the balcony when Anakin destroyed the lava shields leaving the platforms used to collect lava useless. They went onto the platforms and were on one of the arms when it broke off and went into the lava. The two jumped onto lava platforms and dueled. Obi-Wan then jumped onto the shore and told his former apprentice not to jump, but Anakin jumped. Obi-Wan missed and quickly turned around before Anakin could impale him. Obi-Wan used the force to throw ash into Anakin's eyes and throw him head first onto the platform.

Aftermath
Anakin had survived and regained consciousness when Palpatine arrived. Obi-Wan and Padme went to Polis Massa where Padme gave a healthy birth to the twins Luke and Leia. Padme decided to live the remainder of her life on Alderaan giving her position as Senator of Naboo to Jar Jar Binks. Obi-Wan took Luke to hide on Tatooine. Bail Organa took Leia and Padme into hiding. Yoda hid on Dagobah, and R2-D2 and C-3PO went with Bail. On Coruscant, Palpatine explained to Anakin that he had more enemies to find and destroy.