The Battle of Malplaquet (September 11, 1709).
(From the picture by Jan van Huchtenburgh).
While Marlborough was besieging Mons, the French, fearing that the fortress would suffer the fate of Lille and Tournai, marched an army against him. They entrenched themselves in a strong position on the edge of the broken and wooded country which fills the angle between two small rivers which unite at Mons, and were there attacked by Marlborough on September 11, 1709. After what he calls "a very murderous battle" the French were outflanked and their centre was broken through. The British encamped the following night on the French position, but they had lost so many men that they were unable to advance any further that year. You will find this victory referred to in your history books as the Battle of Malplaquet.[23]
John Churchill, first Duke of Marlborough.
(Photo by Walker and Cockerell, from the painting in the National Portrait Gallery.)
In April 1710 the campaign was resumed. Douai was captured, but Arras and the road to France were found to be protected by a line of trenches which foiled even Marlborough. Béthune and other places fell into his hands; but during the winter the French extended their trenches from Namur on the east right to the coast, and the barrier seemed impregnable. In 1711, however, Marlborough carried out a series of movements which are said to be the most wonderful in the whole history of tactics. Early in August he approached the French lines as if about to attack Arras. The French massed their forces to meet him, and in order to do so had to weaken their hold on the trenches farther east. Suddenly, on the same night, Marlborough made a forced march of thirteen leagues to the left. Many of his men dropped from fatigue, but with the remainder he seized a portion of the trenches, and was behind the French lines while the French army was still awaiting his attack on Arras. He had completely outwitted the French general, though, for various reasons, he was unable to take further advantage of his success.
The French trenches of which you have just read ran, roughly, east and west, and were meant to stop an advance on Paris from the north. During the race to the sea the rival armies were moving from the south to the north. Each was trying to outflank the other. The Allies wished to strike eastwards, and the Germans westwards, and the result was that the lines of trenches in which they opposed each other ran from north to south.