The First Peloponnesian War began in 460 BC with the Battle of Oenoe, where Spartan forces were defeated by those of Athenian-Argive alliance. At first the Athenians had the better of the fighting, winning the naval engagements using their superior fleet. They also had the better of the fighting on land, until 457 BC when the Spartans and their allies defeated the Athenian army at Tanagra. The Athenians, however, counterattacked and scored a crushing victory over the Boeotians at the Battle of Oenophyta and followed this victory up by conquering all of Boeotia except for Thebes.