But the League was daily growing in strength and soon returned to the attack. The Imperialists were closely besieged in their turn in Milan, till the descent of Fründsberg with fresh hordes of mercenaries compelled the assailants to retire and concentrate themselves on the defensive against the once again overwhelming Imperialists. Lombardy was now become the complete prey of the occupying armies. The ferocious and undisciplined hosts that nominally served the Emperor no longer heeded the commands of a master who gave them no pay, and was himself far away in Spain. They were practically an independent robber horde, following whom, and going where, they pleased, supporting and enriching themselves on plunder, torturing and murdering peasants and citizens without distinction, to squeeze from them their last possession. It meant nothing to the soldiers that Charles was entering into negotiations for peace with the League. Nor could their captains control them. The Constable de Bourbon, who became Governor of Milan for the Emperor in 1526, promised the afflicted people to move the army from their midst, but even if he had been sincere, he could not have kept his word. Yet the army loved him above all their other leaders, this rebel and exiled prince of France, who was an adventurer like themselves. Before long Milan and the country round was changed into a bare desert, out of which even Spanish cruelty could no longer extract a subsistence. The thought of the unvisited regions farther on began to spread and agitate among the famished hordes; the names of Florence and Rome, cities of untold riches, were breathed from one to another, and as one man they rose at the offer of the Constable de Bourbon to lead them southwards. As a swarm of locusts lifts from a devastated plain, they swept suddenly away on the awful, irresistible course which ended in that final catastrophe of the Middle Ages, the Sack of Rome.