The written instructions given by the Prince to his Lieutenant Sonoy were to "see that the Word of God was preached, without, however, suffering any hindrance to the Roman Church in the exercise of its religion; to restore fugitives and the banished for conscience sake, and to require of all magistrates and officers of guilds and brotherhoods an oath of fidelity." The Prince likewise prescribed the form of that oath, repeating therein, to his eternal honor, the same strict prohibition of intolerance. "Likewise," said the formula, "shall those of 'the religion' offer no let or hindrance to the Roman churches." The Prince was still in Germany, engaged in raising troops and providing funds. He directed; however, the affairs of the insurgent provinces in their minutest details, by virtue of the dictatorship inevitably forced upon him both by circumstances and by the people. In the meantime; Louis of Nassau, the Bayard of the Netherlands, performed a most unexpected and brilliant exploit. He had been long in France, negotiating with the leaders of the Huguenots, and, more secretly, with the court. He was supposed by all the world to be still in that kingdom, when the startling intelligence arrived that he had surprised and captured the important city of Mons. This town, the capital of Hainault, situate in a fertile, undulating, and beautiful country, protected by lofty walls, a triple moat, and a strong citadel, was one of the most flourishing and elegant places in the Netherlands. It was, moreover, from its vicinity to the frontiers of France; a most important acquisition to the insurgent party. The capture was thus accomplished. A native of Mons, one Antony Oliver, a geographical painter, had insinuated himself into the confidence of Alva, for whom he had prepared at different times some remarkably well- executed maps of the country. Having occasion to visit France, he was employed by the Duke to keep a watch upon the movements of Louis of Nassau, and to make a report as to the progress of his intrigues with the court of France. The painter, however, was only a spy in disguise, being in reality devoted to the cause of freedom, and a correspondent of Orange and his family. His communications with Louis, in Paris, had therefore a far different result from the one anticipated by Alva. A large number of adherents within the city of Mons had already been secured, and a plan was now arranged between Count Louis, Genlis, De la Noue, and other distinguished Huguenot chiefs, to be carried out with the assistance of the brave and energetic artist.