The Spaniards were not only driven into the Moro, but they also abandoned the Castle of Chorera; which allowed our immediately breaking ground on the advantageous site of the Cavannos. Never were greater obstacles encountered and overcome, than through the whole series of this siege. The Seamen were highly active in landing the cannon, manning the batteries, and supplying the Army with water, on a spot that yielded not a drop. Much harmony prevailed throughout these fatigues between the services. On the 13th, 800 Marines were landed, formed into two Battalions, under Majors Campbell and Collins, and attached to the command of Colonel and Adjutant General William Howe, upon the Chorera side. Owing to the thinness of soil upon the Cavannos it was not until the 29th of June that our batteries could open against the Moro. In order to obtain a superiority of fire on shore, Captain Harvey, in the Dragon, having under him two other ships, volunteered to place them against that Castle, which he did, in the most gallant stile, upon the morning of the 1st of July. By this diversion the object was gained, but with the loss of Captain Coostrey of the Cambridge, and 161 killed and wounded. The labour of many days was destroyed by a fire that broke out from the dryness of the fascines, and the cannonade kept up, upon the 2d, which was not extinguished until the night of the 5th. Such an unfortunate casualty depressed, but did not conquer the spirits of our men, who were additionally exposed to the most extreme fatigue, a scanty supply of water, and unwholesome provisions.--They had also to encounter an enemy in Don Velasco, worthy of his important trust. Fortunately Sir James Douglas arrived from Jamaica with some reinforcements, which were soon followed by others from North America. It falls not within my scope to enter minutely into the protracted events of this siege, which was carried on and sustained by both sides, with unexampled perseverance, and steady valour. About one o'clock in the afternoon of the 30th of July, by the explosion of one of our advanced mines, a practicable breach for one file in front was effected, which was soon noticed, and assaulted by our troops, at the head of which was Lieutenant Forbes, of the Royal Scotch. Many of the Spanish Soldiers were within the casemates, and little anticipated so bold an attempt, but they were soon under arms, and encouraged to their duty by their brave Chiefs Don Velasco, and the Marquis Gonzales. Both these Gentlemen fell on the occasion; the former surviving only for a short time, the effects of a mortal wound. The Moro was soon carried, which led to the final conquest of the Havannah, and its dependencies upon the 13th of August. Twelve sail of the line, and a large treasure, were its immediate fruits.