No further attempt was made to capture this seemingly impregnable fastness until the great siege here described by Sayer, when once more the Spaniards and French combined against it. England was now somewhat weakened by the war with the American colonies and France. All Europe was unfriendly to her, and Spain, as well as France, was actively hostile. Gibraltar was closely invested in 1779, and so remained for three years, when the final assault was made. In 1782 Alvarez, the Spanish commander, was superseded by the Duc de Crillon, who had just taken Minorca from the British. George Augustus Eliot, afterward Lord Heathfield, Baron of Gibraltar, who made the memorable defence, was appointed governor of Gibraltar in 1775. Lord Howe, who went to his assistance, had conducted the English naval operations in America. He returned to England in 1778, in 1782 was made a viscount of Great Britain, and was sent to relieve Gibraltar, where he arrived too late to assist against the grand attack, but landed welcome troops and supplies. Piqued at the successful defence which for three years had baffled every effort, and burning with the desire to wipe out the stain on the national honor, the Spaniards were urged on in this last struggle by all the impulses of pride, ambition, and revenge. The slow and regular operations of a siege having proved but labor lost against this stubborn rock, rewards were offered to the most skilful engineers in Europe for plans to subdue the fortress. Stimulated by these liberal offers, a thousand schemes had reached Madrid, some bold to extravagance, others too ludicrous to deserve attention. Among them, however, was one, the invention of the Chevalier d'Arçon, of such superior merit that it instantly arrested the attention even of the King himself. His plan consisted of a combined attack by sea and land upon a scale so tremendously formidable, and assisted by such ingenious inventions of art, that it held out a prospect of certain success. After a brief consideration the Court of Madrid announced its unqualified approval of the scheme, and orders were at once issued for its adoption. Not only was the reduction of the fort now considered certain, but so vast were the powers to be employed, and so prodigious the armament to be brought against the walls, that the annihilation of every stone upon the rock was not unexpected. The plan embraced two leading features: first, a bombardment from the isthmus, upon a scale hitherto unknown; secondly, an attack by sea along the whole length of the line-wall. For this purpose floating batteries of such construction that they were to be "at once incombustible and insubmergible," were to be employed.