Among the war party in Athens, a belief arose that the catastrophic defeat of the military expedition to Sicily in 415–413 could have been avoided if Alcibiades had been allowed to lead the expedition. Thus, despite his treacherous flight to Sparta and his collaboration with Sparta and later with the Persian court, there arose a demand among the war party that Alcibiades be allowed to return to Athens without being arrested. Alcibiades negotiated with his supporters on the Athenian-controlled island of Samos. Alcibiades felt that "radical democracy" was his worst enemy. Accordingly, he asked his supporters to initiate a coup to establish an oligarchy in Athens. If the coup were successful Alcibiades promised to return to Athens. In 411, a successful oligarchic coup was mounted in Athens, by a group which became known as "the 400". However, a parallel attempt by the 400 to overthrow democracy in Samos failed. Alcibiades was immediately made an admiral (navarch) in the Athenian navy. Later, due to democratic pressures, the 400 were replaced by a broader oligarchy called "the 5000". Alcibiades did not immediately return to Athens. In early 410, Alcibiades led an Athenian fleet of 18 triremes against the Persian-financed Spartan fleet at Abydos near the Hellespont. The Battle of Abydos had actually begun before the arrival of Alcibiades, and had been inclining slightly toward the Athenians. However, with the arrival of Alcibiades, the Athenian victory over the Spartans became a rout. Only the approach of nightfall and the movement of Persian troops to the coast where the Spartans had beached their ships saved the Spartan navy from total destruction.