In 1557, upon the death of Grand Master Claude de la Sengle, the Knights, mindful of the attack that was sure to come, elected La Valette to be Grand Master. In 1560 he formed an alliance with the Habsburg Empire to reconquer Tripoli, but the expedition resulted in a Christian defeat at the Battle of Djerba. Despite this the Order's galleys were able to rescue several other Christian vessels, and later on in his reign, La Valette greatly strengthened the Order's navy.