As the retreat was to be over the causeway and dykes, a portable bridge was constructed which could be laid across the open canals. This was entrusted to the care of an officer named Magarino and forty men. Cortés arranged the order of march. First was to go two hundred Spanish foot soldiers, commanded by a Captain Sandoval, with twenty other cavaliers. The rear guard was formed of infantry under Alvarado and De Leon, while the center was in charge of Cortés, himself, with some heavy guns, the baggage and the treasure. There were also the prisoners, among whom were a son and two daughters of Montezuma, Cacama, and several nobles. The Indian allies, the Tlascalans, were divided up among the three divisions. There were several thousand of these. Midnight came and all was ready for the journey. A solemn mass was celebrated by Father Almedo, and, keeping as quiet as they possibly could, the Spaniards sallied forth from the ancient palace of the Aztecs, which had been the scene of so much suffering and fighting. The night was a dark one, and a fine, misty rain fell steadily upon the serried columns of Spanish cavaliers and brown-skinned natives. The vast square before the palace was deserted. Through some superstitious dread, the natives had not frequented the plaza since the death of their Emperor, Montezuma, and the Spaniards crossed it as noiselessly as possible, entering the great street of Tlacopan. They peered anxiously into the gloom, expecting to be attacked at any moment by a swarm of Aztecs, but all went well with them until the first files of soldiers drew near the spot where the street opened upon the causeway, which led by the side of the lake. Here there were Mexican sentinels at their posts, and, as the bridge was being adjusted across the uncovered breach, the Aztecs fled, crying out in loud tones that the hated white men were leaving the city. Immediately there was a commotion. The priests heard the shouting from the summits of their _teocalli_ and beat upon the peculiar shells which were used for rousing the people. The huge drum upon the temple of the god of war was struck and gave forth a hollow, moaning roar which vibrated through every corner of the capital. The Spaniards were alarmed and worked with desperate fury to place their bridge across the causeway so that the army could escape. But, as the soldiers labored valorously, a sound was heard like a stormy wind as it rises in a forest. Nearer and nearer it came, and, from the dark waters of the lake came the splashing of many paddles. A few stones and arrows fell among the hurrying troops. More and more followed in rapid succession until they became a veritable blinding storm. Yells and shrill war-cries rent the air, and, before the Spaniards well realized their position, they found themselves surrounded by myriads of the enemy, who were swarming over land and lake.