At two o'clock on the morning of the 11th of May, the allied army advanced to attack the formidable position occupied by the enemy, and the TWELFTH regiment, commanded by Colonel Duroure, was detached with several other corps, under Brigadier-General Ingoldsby, to attack a large fort, mounted with cannon, in the wood of Barri. Against this post the regiment advanced, but the fort was found too formidable to be attacked without artillery, and some delay occurred. Brigadier-General Ingoldsby did not clearly understand his orders, and the regiment was detained a long time in a state of inactivity exposed to a heavy cannonade; during which time the British infantry had forced the enemy's centre, but were obliged to retire in consequence of the Dutch having failed on Fontenoy, and Brigadier-General Ingoldsby having lost the opportunity of attacking the batteries in the wood of Barri. A second attack was, however, determined on, in the hope that the Dutch would make a more determined effort, and the TWELFTH were brought into action; Brigadier-General Ingoldsby was wounded at the head of the regiment, and removed to the rear. Impatient of the state of inactivity in which they had been detained, the soldiers of the TWELFTH rushed into action with distinguished ardour, and were conspicuous for their gallant bearing throughout the remainder of the contest. They were exposed to a heavy fire, and had to contend against very superior numbers. Their commanding officer, Colonel Duroure, fell mortally wounded; Lieut.-Colonel Whitmore was killed; Major Cosseley was wounded, and the command devolved on Captain Rainsford, who was also wounded: but the regiment preserved its firm array, and when more than half the non-commissioned officers and soldiers had fallen, the survivors continued the fight, advancing over the killed and wounded of both armies. The Dutch, however, failed a second time; the British who had penetrated the enemy's line became insulated, and constantly exposed to the attack of fresh troops, and a retreat was ordered; the army withdrawing from the field of battle to Aeth. The conduct of the TWELFTH regiment was commended in the Duke of Cumberland's public despatch; its loss was greater than any other corps in the army, and amounted to _three hundred and twenty-one_ officers and soldiers: viz., Lieut.-Colonel Whitmore, Captain Campbell, Lieutenants Bockland and Lane, Ensigns Cannon and Clifton, five serjeants, and one hundred and forty-eight rank and file killed; Colonel Duroure, Major Cosseley, Captains Rainsford and Robinson, Lieutenants Murray, Townshend, Millington, and Delgaire, Ensigns Dagers and Pearce, seven serjeants, and one hundred and forty-two private soldiers wounded; Captain de Cosne, Captain-Lieut. Goulston, and Lieut. Salt, missing.