Katane was a polis on Sicily. At the time of Alkibiades' Sicilian Expedition, Katane was controlled by a pro-Syracuse faction. After Alkibiades slipped a few men in through a poorly built gate, who allowed his forces to storm the city, the Syracuse faction fled. Katane was relatively welcoming of the Athenians.
Shortly after Katane fell, Alkibiades was recalled to Athens. Instead, he made the fateful decision to press on to Syracuse.