Corfu's earlier sieges and the 1718 catastrophe

Corfu had already faced Ottoman sieges in 1537, 1571, and 1716 before the French takeover. In 1718 lightning struck a powder magazine in the Old Fortress and killed the Doge's brother in an event sometimes called the catastrophe. Each defence demanded more money, manpower, and repair from a republic whose trade returns were already shrinking. The island remained strategically valuable, but maintaining it had stopped producing returns proportionate to the cost.