As a statesman the high qualities of Marlborough were owned by his bitterest foes. "Over the Confederacy," says Bolingbroke, "he, a new, a private man, acquired by merit and management a more decided influence than high birth, confirmed authority, and even the crown of Great Britain, had given to King William." But great as he was in the council, he was even greater in the field. He stands alone amongst the masters of the art of war as a captain whose victories began at an age when the work of most men is done. Though he served as a young officer under Turenne and for a few months in Ireland and the Netherlands, he had held no great command till he took the field in Flanders at the age of fifty-two. He stands alone, too, in his unbroken good fortune. Voltaire notes that he never besieged a fortress which he did not take, or fought a battle which he did not win. His difficulties came not so much from the enemy, as from the ignorance and timidity of his own allies. He was never defeated in the field, but victory after victory was snatched from him by the incapacity of his officers or the stubbornness of the Dutch. What startled the cautious strategists of his day was the vigour and audacity of his plans.

Old as he was, Marlborough's designs had from the first all the dash and boldness of youth. On taking the field in 1702 he at once resolved to force a battle in the heart of Brabant. The plan was foiled by the timidity of the Dutch deputies. But his resolute advance across the Meuse drew the French forces from that river, and enabled him to reduce fortress after fortress in a series of sieges, till the surrender of Liege closed a campaign which cut off the French from the Lower Rhine, and freed Holland from all danger of an invasion. The successes of Marlborough had been brought into bolder relief by the fortunes of the war in other quarters. Though the Imperialist general, Prince Eugene of Savoy, showed his powers by a surprise of the French army at Cremona, no real successes had been won in Italy. An English descent on the Spanish coast ended in failure. In Germany the Bavarians joined the French, and the united armies defeated the forces of the Empire. It was in this quarter that Lewis resolved to push his fortunes.

In the spring of 1703 a fresh army under Marshal Villars again relieved the Bavarian Elector from the pressure of the Imperial forces, and only a strife which arose between the two commanders hindered the joint armies from marching on Vienna. Meanwhile the timidity of the Dutch deputies served Lewis well in the Low Countries. The hopes of Marlborough, who had been raised to a Dukedom for his services in the previous year, were again foiled by the deputies of the States-General. Serene as his temper was, it broke down before their refusal to co-operate in an attack on Antwerp and French Flanders; and the prayers of Godolphin and of the pensionary Heinsius alone induced him to withdraw his offer of resignation. But in spite of his victories on the Danube, of the blunders of his adversaries on the Rhine, and the sudden aid of an insurrection which broke out in Hungary, the difficulties of Lewis were hourly increasing. The accession of Savoy to the Grand Alliance threatened his armies in Italy with destruction.

That of Portugal gave the allies a base of operations against Spain. The French King's energy however rose with the pressure; and while the Duke of Berwick, a natural son of James the Second, was despatched against Portugal, and three small armies closed round Savoy, the flower of the French troops joined the army of Bavaria on the Danube; for the bold plan of Lewis was to decide the fortunes of the war by a victory which would wrest peace from the Empire under the walls of Vienna.

The master-stroke of Lewis roused Marlborough at the opening of 1704 to a master-stroke in return; but the secresy and boldness of the Duke's plans deceived both his enemies and his allies. The French army in Flanders saw in his march upon Maintz only a design to transfer the war into Elsass. The Dutch were lured into suffering their troops to be drawn as far from Flanders as Coblentz by proposals for an imaginary campaign on the Moselle. It was only when Marlborough crossed the Neckar and struck through the centre of Germany for the Danube that the true aim of his operations was revealed. After struggling through the hill country of Wurtemberg, he joined the Imperial army under the Prince of Baden, stormed the heights of Donauwerth, crossed the Danube and the Lech, and penetrated into the heart of Bavaria. The crisis drew the two armies which were facing one another on the Upper Rhine to the scene. The arrival of Marshal Tallard with thirty thousand French troops saved the Elector of Bavaria for the moment from the need of submission; but the junction of his opponent, Prince Eugene, with Marlborough raised the contending forces again to an equality.

After a few marches the armies met on the north bank of the Danube, near the little town of Hochstadt and the village of Blindheim or Blenheim, which have given their names to one of the most memorable battles in the history of the world. In one respect the struggle which followed stands almost unrivalled, for the whole of the Teutonic race was represented in the strange medley of Englishmen, Dutchmen, Hanoverians, Danes, Wurtembergers and Austrians who followed Marlborough and Eugene. The French and Bavarians, who numbered like their opponents some fifty thousand men, lay behind a little stream which ran through swampy ground to the Danube. Their position was a strong one, for its front was covered by the swamp, its right by the Danube, its left by the hill-country in which the stream rose; and Tallard had not only entrenched himself, but was far superior to his rival in artillery. But for once Marlborough's hands were free. "I have great reason," he wrote calmly home, "to hope that everything will go well, for I have the pleasure to find all the officers willing to obey without knowing any other reason than that it is my desire, which is very different from what it was in Flanders, where I was obliged to have the consent of a council of war for everything I undertook." So formidable were the obstacles, however, that though the allies were in motion at sunrise, it was not till midday that Eugene, who commanded on the right, succeeded in crossing the stream.