Taught by the bitter experience of Caen, the burghers began their preparations by devastating the buildings in St. Sever on the south side of the bridge, and before the invaders were close up, they practically levelled to the ground nearly every house in the faubourgs outside the fortifications. With the stone thus sacrificed, they repaired the breaches in their walls, and strengthened every tower, sowing "chausse-trappes," or sharp three-pronged irons in the fields all round the city. Besides the cannon on the walls, each tower had three large guns pointing in different directions, and eight smaller pieces for fast firing. Antiquated weapons were pressed into the service as well, the balista, the three-mouthed trebuchet (the tappgete, or tryppgette of the English), and the sling for hurling heavy darts and arrows set up on the Porte Martainville. Besides this, they sank every boat on the Seine, above or below the town, and even burnt their two royal galleys when the progress of the siege compelled them to prevent the English from the advantage of their capture. Further taxes were raised and cheerfully paid by layman, ecclesiastic, and soldier alike, and orders were issued, by the sound of a trumpet in every public square, that every householder should get in provisions for ten months, an almost impossible feat considering the scarcity of all food in Normandy at the time. Finally, some thousands of the poorer classes were banished out of the town, and a few drifted as far as Beauvais and Paris, but the majority were swept back again into Rouen by the constantly increasing tide of fugitives driven into the city by the English, to make the task of feeding so many useless mouths more difficult. The results were hideous when the famine came. On the English side, the King's own men numbered 16,400 of all arms, the contingents of his various captains and barons amounted to 20,306, including knights, light cavalry, and archers on foot. In addition, 1000 carpenters and workmen followed the army, with some 6000 engineers, sappers, and miners including the men who served the artillery. This was the force that left England, and any diminutions in it, by lapse of time and service, were more than made up by the reinforcements of the Earl of March, of the Duke of Exeter, of Sir John Talbot, and the Prior of Kilmaine. So that the total of the army that besieged Rouen was, at least, 45,000 men. This large force was brought across the Seine, partly by the old bridge of Pont de l'Arche, partly by a light and ingenious pontoon bridge made of planks supported on watertight leather boats, which could be packed up and carried with the army on the march.