The attack began next morning with a bombardment of the Tower of St Nicholas. This was the large fort, with walls twenty-four feet thick, which stood at the end of the long mole that divided the Mandraccio from the commercial port. If it could be reduced both harbours would immediately become vulnerable. Meanwhile innumerable other cannons of varying weight began to bombard the city itself, hurling their projectiles high over the walls with the object of demoralising the townsfolk, none of whom had ever before experienced the violence of modern war. D’Aubusson, however, with his usual foresight had already organised shelters in cellars throughout the city where the women and children, and the old and the sick, could take refuge.

Strong though it was, St Nicholas began to crumble before the weight of the gunfire. D’Aubusson, realising that almost everything hinged upon its preservation from the enemy, immediately set about converting its ruins into an even stronger fortress. (Now that its profile was reduced its actual thickness was almost doubled.) He knew that if it fell not only would the harbours become untenable, but the Turks would be able to storm along the mole and attack the two city gates at its landward end. During the days and nights that followed gangs of slaves, soldiers and townspeople laboured continually to maintain the structure of the tower and at the same time convert the whole mole into a walled rampart facing the Turks across the waters of the Mandraccio.

On May 28th the Grand Master sent off an urgent despatch to all members of the Order in Europe. He implored their help and angrily pointed out that many of the brethren had already turned a deaf ear to his previous pleas and exhortations. The situation, he said, was critical, and no member who failed to do all in his power to come to the Order’s assistance could even be excused. ‘What is more sacred than to defend the Faith?’ he concluded. ‘What is happier than to fight for Christ?’ But the fact was that in those days of poor communications and worse travel facilities Rhodes was just too far away for many members of the Order ever to reach it on short notice. Even if they were to band together and equip a ship, by the time they had done so and reached the island all would be over one way or another. There was the likelihood too that if the island was as closely invested by a large fleet as it appeared to be, then a relief force would have no chance of getting through. Surprisingly enough, only a few days later a relief vessel did get through and make its way into the commercial port. This was a Sicilian carrack, laden with grain and a number of reinforcements—very helpful to morale at this stage in the siege.

On the same day that d’Aubusson wrote his letter to the absent brethren a very strange defector made his way over from the Turkish lines and asked to be let into the city. This was none other than Master George, the great German artillery expert, regarded as the main brains behind the siting of the cannon and the conduct of the bombardment. Like so many who served in the Turkish ranks he was a Christian by birth. As he told d’Aubusson when he was interviewed, his heart had been moved by the plight of his co-religionists and he wished to join them and give his services to the Holy Religion. D’Aubusson received him courteously enough and accepted the offer. At the same time he detailed six Knights to form a permanent bodyguard for the master-gunner, telling them never to let him out of their sight, and to watch and report on everything he said and did. D’Aubusson was no man’s fool and the defection, particularly of so important a figure in the Sultan’s camp, seemed a little too easy. Meanwhile the main weight of the bombardment continued to fall upon the Tower of St Nicholas and it was clear that before very long the Turk would come to the attack.

The blow fell early one June morning, when specially modified Turkish triremes were seen rounding Akra Milos from their base at Trianda and heading across the misty sea for the fortress. The vessels had had their masts, spars and rigging removed, and were fitted with special fighting platforms in the bows. Manned by Sipahi troops, professionals second only to the crack Janissaries, they came onward towards their objective to the usual clamour of cymbals, drums, pipes and ululating cries with which the Turks always went into battle. The Knights and men-at-arms were waiting for them. While the advancing ships kept up a steady fire on the fort, all the guns that could be brought to bear opened fire upon them, from the fort itself and from the Post of France, that part of the city wall which faced the mole. The attackers were brave enough, hurling themselves off the bow-platforms into the sea and swarming ashore. But they were committing the unforgivable mistake of attempting a landing right in the face of a strongly fortified and strongly held position. (If the Turkish command had over-estimated the damage that their bombardment had done and had reckoned that the defence must be almost non-existent, they were to be sadly disillusioned.) Even as the first wave of Sipahis attempted to come ashore they were met by a withering fire from crossbows, arquebuses and long bows, while for those who actually managed to reach the palisades erected round the fort there waited the sizzle of Greek fire.