The story of the sixteenth-century revolution in the Low Countries is so well known that it is scarcely necessary to recall again here the details of events. From the point of view of the formation of Belgian nationality, the revolution has an extraordinary importance, since it engendered the separation of the Low Countries into two distinct nationalities, which were later to be known as Belgian and Dutch. Most English readers who remember their Motley, or any of the less valuable writings he inspired, are under the impression that if the Belgians did not adopt the same attitude as the Dutch all through the struggle against Spain, it was either because they were blinded by their religious prejudices or because their patriotism did not rise to the same exalted height. Such an opinion is perfectly plausible, but it does not sufficiently take into account the intransigent and selfish attitude adopted by the Northern provinces, the political mistakes committed by their leader, and the difference between the strategical position and the economic interests of the revolutionaries in the North and in the South of the country. It may therefore be useful to examine the efforts made towards unity during the struggle and the causes of their failure. The steps taken by the Calvinist nobles which resulted in the failure of de Marnix to seize Antwerp (March 13th) and the taking of Valenciennes by Government troops (March 24th) were followed by a strong reaction. The placards were again enforced, and a rumour began to spread that the Duke of Alba was being sent by Philip to the Netherlands at the head of a strong army. At this news over a hundred thousand Protestants emigrated to England or to the North.