In 1540 emperor Charles V, assisted by a team of military experts, decided to provide Antwerp, the most important city of the Netherlands at that time, with a new wall designed by an Italian engineer, Donato Boni. From that moment until 1609, the year of the beginning of the Twelve Year's Truce, more than sixty Italian engineers worked in the Low Countries. These Italian engineers not only modernized the medieval walls with a new defence system based on flanking by means of bastions, but also built new settlements and citadels. Even when their military buildings were replaced by new Dutch fortifications, the defence principle of attacking the enemy in the flank from protruding bastions remained unchanged. The way this fudamental change of the defensive works, which conditioned the further development of the Dutch city far into the nineteenth century, had been introduced from Italy, has hardly got any attention in the history of architecture. . Zie: Summary.