The rapid development of the arts of the engineer and artillerist aimed another heavy blow at the Swiss supremacy. The many-sided energy of the Renaissance period not unfrequently made the professional soldier a scholar, and set him to adapt the science of the ancients to the requirements of modern warfare. The most cursory study of Vegetius Hyginus or Vitruvius, all of them authors much esteemed at the time, would suffice to show the strength of the Roman fortified camp. Accordingly the art of Castramentation revived, and corps of pioneers were attached to every army. It became common to intrench not merely permanent positions, but camps which were to be held for a few days only. Advantage was taken of favourable sites, and lines of greater or less strength with emplacements for artillery were constructed for the protection of the army which felt itself inferior in the field. Many of the greatest battles of the Italian wars were fought in and around such positions; Ravenna, Bicocca, and Pavia are obvious examples. Still more frequently a general threw himself with all his forces into a fortified town and covered it with outworks and redoubts till it resembled an intrenched camp rather than a mere fortress. Such a phase in war was most disadvantageous to the Swiss: even the most desperate courage cannot carry men over stone walls or through flooded ditches, if they neglect the art which teaches them how to approach such obstacles. The Confederates in their earlier days had never displayed much skill in attacking places of strength; and now, when the enemy’s position was as frequently behind defences as in the open plain, they refused to adapt their tactics to the altered circumstances. Occasionally, as for example at the storming of the outworks of Genoa in 1507, they were still able to sweep the enemy before them by the mere vehemence of their onset. But more frequently disaster followed the headlong rush delivered against lines held by an adequate number of steady troops. Of this the most striking instance was seen in 1522, when the Swiss columns attempted to dislodge the enemy from the fortified park of Bicocca. Under a severe fire from the Spanish hackbut-men they crossed several hedges and flooded trenches, which covered the main position of the imperialists. But when they came to the last ditch and bank, along which were ranged the landsknechts of Frundsberg, they found an obstacle which they could not pass. Leaping into the deep excavation the front ranks endeavoured to scramble up its further slope; but every man who made the attempt fell beneath the pike-thrusts of the Germans, who, standing on a higher level in their serried ranks, kept back the incessant rushes with the greatest steadiness. Three thousand corpses were left in the ditch before the Swiss would desist from their hopeless undertaking; it was an attack which, for misplaced daring, rivals the British assault on Ticonderoga in 1758.