The triple line of strong fortresses possessed by the French on the borders of Belgium served Napoleon as a curtain, behind which he could prepare his levies and unite his forces at pleasure, without any possibility of the allies or their generals being able to observe his motions, or prepare for the attack which such motions indicated. On the other hand, the frontier of Belgium was open to his observation, and he knew perfectly the general disposal of the allied force. If the French had been prepared to make their meditated attack upon Flanders in the month of May, they would have found no formidable force to oppose them, as at that time the armies of the Prussian general Kleist, and the hereditary Prince of Orange, did not, in all, exceed 50,000 men. But the return of Napoleon, which again awakened the war, was an event as totally unexpected in France as in Flanders, and, therefore, that nation was as much unprepared to make an attack as the allies to repel one. Thus it happened, that while Napoleon was exerting himself to collect a sufficient army by the means we have mentioned, the Duke of Wellington, who arrived at Brussels from Vienna in the beginning of April, had leisure to garrison and supply the strong places of Ostend, Antwerp, and Nieuport, which the French had not dismantled, and to fortify Ypres, Tournay, Mons, and Ath. He had also leisure to receive his reinforcements from England, and to collect the German, Dutch, and Belgian contingents. Thus collected and reinforced, the Duke of Wellington's army might contain about 30,000 English troops. They were not, however, those veteran soldiers who had served under him during the Peninsular war; the flower of which had been despatched upon the American expedition. Most were second battalions, or regiments which had been lately filled up with new recruits. The foreigners were 15,000 Hanoverians, with the celebrated German Legion, 8000 strong, which had so often distinguished itself in Spain; 5000 Brunswickers, under their gallant duke; and about 17,000 Belgians, Dutch, and Nassau troops, commanded by the Prince of Orange.