Marlborough arrived at the Hague on the 4th March; and, although no longer possessing the confidence of government, or intrusted with any control over diplomatic measures, he immediately set himself with the utmost vigour to prepare for military operations. Great efforts had been made by both parties, during the winter, for the resumption of hostilities, on even a more extended scale than in any preceding campaign. Marlborough found the army in the Low Countries extremely efficient and powerful; diversions were promised on the side both of Spain and Piedmont; and a treaty had been concluded with the Spanish malcontents, in consequence of which a large part of the Imperial forces were rendered disposable, which Prince Eugene was preparing to lead into the Low Countries. But, in the midst of these flattering prospects, an event occurred which suddenly deranged then all, postponed for above a month the opening of the campaign, and, in its final result, changed the fate of Europe. This was the death of the Emperor Joseph, of the smallpox, which happened at Vienna on the 16th April – an event which was immediately followed by Charles, King of Spain, declaring himself a candidate for the Imperial throne. As his pretensions required to be supported by a powerful demonstration of troops, the march of a large part of Eugene's men to the Netherlands was immediately stopped, and that prince himself was hastily recalled from Mentz, to take the command of the empire at Ratisbon, as marshal. Charles was soon after elected Emperor. Thus Marlborough was left to commence the campaign alone, which was the more to be regretted, as the preparations of Louis, during the winter, for the defence of his dominions had been made on the most extensive scale, and Marshal Villars' lines had come to be regarded as the ne plus ultra of field fortification. Yet were Marlborough's forces most formidable; for, when reviewed at Orchies on the 30th April, between Lille and Douay, they were found, including Eugene's troops which had come up, to amount to one hundred and eighty-four battalions, and three hundred and sixty-four squadrons, mustering above one hundred thousand combatants.28 But forty-one battalions and forty squadrons were in garrison, which reduced the effective force in the field to eighty thousand men.
The great object of Louis and his generals had been to construct such a line of defences as might prevent the irruption of the enemy into the French territory, now that the interior and last line of fortresses was so nearly broken through. In pursuance of this design, Villars had, with the aid of all the most experienced engineers in France, and at a vast expense of labour and money, constructed during the winter a series of lines and field-works, exceeding any thing yet seen in modern Europe in magnitude and strength, and to which the still more famous lines of Torres Vedras have alone, in subsequent times, afforded a parallel. The works extended from Namur on the Meuse, by a sort of irregular line, to the coast of Picardy. Running first along the marshy line of the Canche, they rested on the forts of Montreuil, Hesdin, and Trevant; while the great fortresses of Ypres, Calais, Gravelines, and St Omer, lying in their front, and still in the hands of the French, rendered any attempt to approach them both difficult and hazardous. Along the whole of this immense line, extending over so great a variety of ground, for above forty miles, every effort had been made, by joining the resources of art to the defences of nature, to render the position impregnable. The lines were not continuous, as in many places the ground was so rugged, or the obstacles of rocks, precipices, and ravines were so formidable, that it was evidently impossible to overcome them. But where*ever a passage was practicable, the approaches to it were protected in the most formidable manner. If a streamlet ran along the line, it was carefully dammed up, so as to be rendered impassible. Every morass was deepened, by stopping up its drains, or letting in the water of the larger rivers by artificial canals into it; redoubts were placed on the heights, so as to enfilade the plains between them; while in the open country, where no advantage of ground was to be met with, field-works were erected, armed with abundance of heavy cannon. To man these formidable lines, Villars had under his command one hundred and fifty-six battalions, and two hundred and twenty-seven squadrons in the field, containing seventy thousand infantry, and twenty thousand horse. He had ninety field guns and twelve howitzers. There was, besides, thirty-five battalions and eighty squadrons detached or in the forts; and, as Eugene soon took away twelve battalions and fifty squadrons from the Allied army, the forces on the opposite side, when they came to blows, were very nearly equal.29
Marlborough took the field on the 1st May, with eighty thousand men; and his whole force was soon grouped in and around Douay. The headquarters of Villars were at Cambray; but, seeing the forces of his adversary thus accumulated in one point, he made a corresponding concentration, and arranged his whole disposable forces between Bouchain on the right, and Monchy Le Preux on the left. This position of the French marshal, which extended in a concave semicircle with the fortresses, covering either flank, he considered, and with reason, as beyond the reach of attack. The English general was meditating a great enterprise, which should at once deprive the enemy of all his defences, and reduce him to the necessity of fighting a decisive battle, or losing his last frontier fortresses. But he was overwhelmed with gloomy anticipations; he felt his strength sinking under his incessant and protracted fatigues, and knew well he was serving a party who, envious of his fame, were ready only to decry his achievements.30 He lay, accordingly, for three weeks awaiting the arrival of his illustrious colleague, Prince Eugene, who joined on the 23d May, and took part in a great celebration of the anniversary of the victory at Ramilies, which had taken place on that day. The plans of the Allied generals were soon formed; and, taking advantage of the enthusiasm excited by that commemoration, and the arrival of so illustrious a warrior, preparations were made for the immediate commencement of active operations. On the 28th, the two generals reviewed the whole army. But their designs were soon interrupted by an event which changed the whole fortune of the campaign. Early in June, Eugene received positive orders to march to Germany, with a considerable part of his troops, to oppose a French force, which was moving towards the Rhine, to influence the approaching election of Emperor. On the 13th June, Eugene and Marlborough separated, for the last time, with the deepest expressions