James was very serious about fulfilling his part of the treaty of 1295 and enforcing a peace. In this he had the support of John of Procida and Roger of Lauria, his father's ablest men. On 4 July 1299, James himself led his fleet with Roger of Lauria and defeated his brother at the Battle of Cape Orlando. Meanwhile, Charles' sons, Robert (who had married James' daughter) and Philip, had landed in Sicily and captured Catania. Philip moved to besiege Trapani, but was defeated and captured by Frederick at the Battle of Falconaria. Frederick multiplied his successes in Calabria. On 14 June 1300, Roger of Lauria defeated the Sicilians again at the Battle of Ponza. Frederick himself was captured in battle.