Once the troops had all taken their positions on the Outer Wall, the gates of the Inner Wall were closed and locked behind them. There was to be no retreat. In the Mesoteichion the relentless pounding of the Turkish cannons had completely leveled a section of the Outer Wall, and half a dozen towers, had helped to fill in the moat. Mohammed's troops had finished this work so that now the moat before this broken section was completely filled. Also destroyed in this sector were two towers of the Inner Wall. Here Giustiniani, who had moved his headquarters to this threatened sector early in the siege, prepared to withstand the Turkish onslaught with two thousand men. Under his direct command were the best of the Greeks and his own troops included four hundred Genoese cuirassiers with their glittering breastplates.

Their only protection was the jerrybuilt parapet of planks, tree trunks and branches, even crates filled with straw. All this was stuck together with ladders, earth and clay. As a protection against fire arrows, the wooden facings of the parapet were covered with hides. Atop of all this, forming crenellations, were barrels filled with earth.

At sunset the Turks erupted into action. The defenders watched impassively as the Turks completed the work of filling the moat and hauled their cannons forward to point-blank range. Shortly after 1 a.m. of May 29th, the Sultan Mohammed decided everything was ready. He ordered the assault. The signal was a fanfare of trumpets and a tattoo of drums. Along the four-mile front thousands of Turkish troops roared their battle cries and charged the walls. As the Christian soldiers braced themselves for the shock of the assault, the city's bells began to peal to warn the populace the attack had begun. Women and children, elderly men, nuns and invalids hurried to their parish churches to pray.

The honor of the first wave had been granted to the Bashi-bazouks. These numerous divisions were a hodgepodge of Turks, Slavs, Germans, Italians, Hungarians - even Greeks - who were more akin to mercenaries than regular troops. Their only pay was the booty they could seize. They provided their own weapons - an assortment of swords, spears, bows, slings, flails and a few arquebuses. For this night they had been provided with scaling ladders. A pale moon illuminated the frenzied scene.

The Bashi-bazouks were fearsome troops on the first pell mell charge, but they were easily discouraged if they were repulsed. Mohammed had prepared for this. Behind these irregulars he had lined up his military police. They were armed with whips and truncheons. Any man who filtered was to be beaten back to the attack. If any deserted through the police lines they would be confronted by ranks of Janissaries deployed behind the police. The Janissaries had strict orders regarding deserters - cut them down.

This attack had been launched along the entire land wall, but the main weight was concentrated on the Mesoteichion. Mohammed saw the pathway to victory here. The rest was a huge diversionary onslaught to weary the defenders.

The huge numbers of Bashi-bazouks, and their undisciplined eagerness to break into the city, was more of an impediment than a help. They crowded together so tightly at the base of the walls and stockades that they were barely able to discharge their arrows. The arrows hailed down on them from the walls rarely missed a target. Boulders hurled down onto the mass of struggling men often hit two or three. And as the Bashi-bazouks scaled their ladders to the parapets they encountered soldiers far better trained and armed. Guistiniani had seen to it that this time his men at the vulnerable Mesoteichion were provided with all the city's available culverins and muskets. These fire arms added to the carnage of the Bashi-bazouks.

This attack lasted for two hours. When the retreat was sounded, the defenders were grateful for the respite. There was not a man on the walls who was not now utterly exhausted. A few of their comrades moaned at their feet in pools of blood. In some sections there were no missile weapons left. Here the troops were reduced to reliance on their swords and shields.

So far Mohammed was satisfied. He knew his fleets had launched their attacks. The entire fourteen miles of the city's walls were in a state of alarums. He had not expected the Bashi-bazouks to break the defenses, but they had done their job. Men's arms could only hack and thrust so long.

The weary defenders on the walls had barely time to catch their breaths before the growing thunder of thousands of horses' hooves came from the darkness. The Christians made what hasty repairs they could and reformed their lines.

The second wave was composed entirely of divisions from Asia Minor, the regular cavalry militia. These men were distinctive by their uniforms and breastplates. They wheeled their mounts into long lines before the Mesoteichion and dismounted.

Suddenly Urban's cannon roared, followed immediately by the bark of the smaller guns. The salvo pounded into the defenses showering splinters and rocks, slamming down planks and enveloping the Christians in a choking dust. The trumpets and fifes blared and with roars and oaths the Turks raced forward.

They flung their ladders against the defenses and clambered up lunging and hacking at the defenders. These were pious Moslems every man believing that upon his death in battle he would be transported to the gardens of Paradise and the embrace of dusky virgins. There was not a man who did not lust for the treasures of the city, yet none feared to die.

With desperate determination the Christians hacked at the shadowy invaders in the dim light of the veiled moon. They toppled back the Turkish ladders, and where the attackers managed to mount to the top of their palisades they fought hand to hand.

Further south at the Third Military Gate the European divisions of the Ottomans were less effective. Here the walls were still largely intact. However, the pressure was intense enough to prevent the Christians from risking the movement of reinforcements to the Mesoteichion. In quiet places along the walls stealthy groups of Turks in the dark shadows cast by towers silently attempted to scale the walls to catch the defenders by surprise. Even where there was no fighting the Christians had to maintain a nerve-wracking vigilance.

Along the Marmora Sea walls the Turkish navy managed to land scattered parties among the shoals. These groups were easily beaten back to the boats by the monks and the Turks of Prince Orhan. The fleet in the Golden Horn made numerous clamorous feints against the walls but no serious attack was launched. The Turks made a determined effort against the Blachernal. Here, too, they were held off.

Shortly before dawn the main attack at the Mesoteichion began to waver. At this moment, however, Urban's cannon fired another shot over a section of the moat that had never been filled. The huge ball of stone slammed squarely into a section of wooden stockade and knocked it down. Immediately a detachment of several hundred Turks nearby rushed toward the gap with hoarse shouts of triumph. Luckily Constantine was on the scene. He personally led his Greeks against the Turks who were now rushing over the fallen palisade. Here was the bitterest and bloodiest battle of the long night. The Turks charged up to the ordered ranks of Christian shields. Then it was man to man, slashing and thrusting, steel clanging on steel. Before long the Turks were pushed back though the gap. But the Christians weren't satisfied. They were enraged. They continued to cave the Turks back until they were toppling into 'IC moat. Few Turks survived.

The Greeks paused briefly to shout derision at the fleeing remnants of their enemy, then they returned to the battlements and began to repair the damage. This was the psychological stroke that broke the attack. The general retreat was sounded and once again a silence descended on the battlefield. It was but another brief respite for the exhausted defenders. Mohammed now made the decisive gamble that would win or end the siege.