Victory of the Sith

The Duel on Mustafar was the event in the Great Jedi Purge in which Obi-Wan Kenobi was killed by Darth Vader. 
The duel occured in the aftermath of the Mission to Mustafar, in which Darth Vader slaughtered the Separatist Council and ended the Clone Wars. He met up with his wife, Padme Amidala, during the aftermath of the massacre. Obi-Wan Kenobi, hiding in the cargo hold of her Naboo Skiff, appeared to Vader, making it seem like it was a trap laid out by Padme. In his rage, Vader strangled his wife to near death, knocking her unconscious. The former best friends were forced to confront each other in battle. 
The two battled each other on the landing platform and made their way through the hallways of Klegger Corp Mining Facility. In the conference room, Vader forced Kenobi's lightsaber handle into his throat, temporarily paralyzing him, and attempted to decapitate his former master. Kenobi held him off as best as he could. Kenobi managed to fling himself out of his former Padawan's grasp. Then, he knocked Anakin down and calling his lightsaber to his hand, tried to kill him. He failed and the two proceeded into the control room. The two forced each other into opposite ends of the room with a combined Force Push. Attempting to kill Kenobi, Vader jumped at the Jedi and missed, accidentaly destroying the controls for the facility's shields, allowing heat and flying lava to weaken the the collection arm systems outside the complex. 
As the two dueled on Anakin forced Kenobi back in a furious attack. While this was going on the lava collection arm outside, the lack of shielding proved too much for the superstructure, bringing it down. It smashed into the river of lava, and both contestants barely held on for dear life. The lava river below dragged the collection arm down a lava-fall and nearly killed Vader. However, both he and Kenobi managed to leap off the arm, landing on a droid lava collector, and a repulsorlift platform, respectively. 
It was then that Kenobi was able to accept Anakin had fallen and allowed himself to become more intent on killing Skywalker. As the two dueled their way to the shore, Obi-Wan jumped and gained the high ground. In his rage and confidence, Vader leaped over Kenobi, who slashed up....and missed. Vader took advantage of Kenobi's distraction and stabbed him through the chest. 
Vader smirked at his victory, retrieved Kenobi's lightsaber, and then kicked his old friend's corpse into the lava river and left for the landing platform. 
Vader returned to the Star Skiff and helped R2-D2 and C-3PO carry Padme into the ship. He put the protocol droid in charge of flying the larger ship, while the Sith Lord escorted them back to Coruscant in his Jedi Interceptor. 
They returned to a medical facility in the capital city, where Padme, R2-D2, and C-3PO were convinced by Vader that he was not evil. With that horror out of her mind, Padme healthily gave birth to Luke and Leia.