Timeline

Sisko and Janeway meet in the past and decide to cooperate to try to change history to prevent Picard from ever coming to power. Meanwhile Picard became a colonel in the British military and was secretly helping the Nazis to win WW2 (both by giving the Nazis advanced technology and by being a mole in the British top brass. He planned to wait until the Nazis take over the world and to later take Hitler's place, but Martok beamed down Klingon ground troops which defeated the Nazis, thwarting Picard's plans. Picard used the nazi space cannon to destroy the bird of prey and later Voyager, and captured and executed Chakotay and Torres who escaped in a shuttle, believing them to be responsible for killing his son Hitler (who was conceived by Picard decades earlier). But Quark was also on the bird of prey and was found at Roswell and wanted to become a supreme ruler himself so he made himself known to the public and later became Earth's ruler. Quark then gave advanced technology to the Ferengi and made the Ferengi race the top-class of the future Federation society. Back in the future the Enterprise's captain is now a Ferengi. Since Picard still has memory of how things used to be before, he recognizes the change in the time-line and immediately acts to go back to the past again.