The value of his services was soon made evident. Twice, at the head of very inferior troops, he checked Conde in the career of victory; and again compelled him to fight under the walls of Paris; where, in the celebrated battle of the Faubourg St. Antoine, the prince and his army narrowly escaped destruction. Finally, he re-established the Court at Paris, and compelled Conde to quit the realm. These important events took place in one campaign of six months in 1652. In 1654 he again took the field against his former friend and commander, Conde, who had taken refuge in Spain, and now led a foreign army against his country. The most remarkable operation of the campaign was the raising the siege of Arras, which the Spaniards had invested, according to the most approved fashion of the day, with a strong double line of circumvallation, within which the besieging army was supposed to be securely sheltered against the sallies of the garrison cooped up within, and the efforts of their friends from without. Turenne marched to the relief of the place. This could only be effected by forcing the enemy's entrenchments; which were accordingly attacked, contrary to the opinion of his own officers, and carried at all points, despite the personal exertions of Conde. The Spaniards were forced to retreat. It is remarkable that Turenne, not long after, was himself defeated in precisely similar circumstances, under the walls of Valenciennes, round which he had drawn lines of circumvallation. Once more he found himself in the same position at Dunkirk. On this occasion he marched out of his lines to meet the enemy, rather than wait, and suffer them to choose their point of attack; and the celebrated battle of the Dunes, or Sandhills, ensued, in which he gained a brilliant victory over the best Spanish troops, with Conde at their head. This took place in 1657. Dunkirk and the greater part of Flanders fell into the hands of the French in consequence; and these successes led to the treaty of the Pyrenees, which terminated the war in 1658.