In the preceding year, aided by Florence and the League, Lucca had taken the field with four hundred horse and two thousand foot, in order to carry on the war with Pisa, while the Florentines were busied with Arezzo. This force encamped before Pisa, and, according to usage, held races there; harried the territory for twenty-five days, captured the Castle of Caprona, and made several assaults on Vico Pisano, but achieved no farther result. Now, in 1290, the Florentines resumed the attack in combination with all the great forces of the League. And while this army was making a general attack by land, the Genoese fleet swooped down on the coast with deadly effect. Leghorn and Porto Pisano were taken, the four towers guarding the harbour were thrown into the sea, and the Meloria lighthouse destroyed in the same way, together with its keepers. Before setting sail the Genoese blocked the mouth of the harbour by sinking four ships laden with ballast, and demolished all warehouses and palaces. But the havoc wrought by land was confined to the destruction of crops and the demolition of petty strongholds. Meanwhile the Pisans made a brave resistance on all sides. Guido di Montefeltro, their captain, used his newly invented troop of light horse to excellent effect against the Tuscan infantry of the League and the heavy cavalry in its pay. By his successful sallies he repeatedly achieved a bloody revenge for past losses. In December, 1291, the Pisans marched on the Castle of Pontedera, and finding it slackly defended, accomplished its capture, and shortly afterwards stirred the Castle of Vignale to revolt against San Miniato. Thereupon the Florentines decided on sending an army to provoke a fresh engagement; but the expedition was too long delayed, and the troops had hardly started before torrents of rain inundated the country and compelled them to retreat.