From the peace which Gian Galeazzo had enforced at home, as much as from his conquests abroad, there had ensued a prosperity such as Milan had never known before. Her industries throve apace. Her weavers of silk and wool sent their products to Venice, to France, to Flanders, and to England; the work of her armourers was sought by all Europe; great was the trade driven with France in horses and fat Lombardy cattle. Thus the wealth of the civilised world was drawn to Milan, and such was the development there of banking that soon there was scarcely an important city in Europe that had not its Lombard Street, just as in every city of Europe the gold coins of Gian Galeazzo, bearing his snake device, circulated freely, coming to be known as ducats in honour of this first Duke of Milan. His laws, if tinctured by the cruelty of an age which held human lives cheap, were nevertheless wise and justly administered; and he knew how to levy taxes that should enrich himself without impoverishing his subjects, perceiving with an intuition altogether beyond his age that excessive taxation serves but to dry up the sources of a prince's treasury. His wealth he spent with a staggering profusion, creating about himself an environment of beauty, of art, and of culture which overwhelmed the rude French and ruder English of his day with the sense of their own comparative barbarism. He spent it also in enlisting into his service the first soldiers of his time; and by reducing a score of petty tyrannies and some that were of consequence, the coils of the viper came to extend from the Alps to the Abruzzi. So wide, indeed, were his dominions become that they embraced the greater part of Northern Italy, and justified their elevation to the status of a kingdom and himself to the assumption of the royal crown. In the Castle of Melegnano, where he had shut himself up to avoid the plague that was crawling over the face of Italy, the regalia was already prepared when this great prince, whom no human enemy had yet been able to approach, was laid low by the invincible onslaught of that foul disease. Because at the time of their great father's death Gian Maria was thirteen and Filippo Maria twelve years of age, they remained, as Gian Galeazzo's will provided against such a contingency, under the tutelage of a council of regency composed of the condottieri and the Duchess Catherine.