In 1666, a Venetian attempt to recapture La Canea failed. The following year, Colonel Andrea Barozzi, a Venetian military engineer, defected to the Ottomans and gave them information on weak spots in Candia's fortifications. On 24 July 1669, a French land/sea expedition under Mocenigo not only failed to lift the siege, but also lost the fleet's vice-flagship, "La Thérèse" a 900-ton French warship armed with 58 cannons, to an accidental explosion. This dual disaster was devastating to the morale of the city's defenders.