Soult instantly destroyed the communications, and rendered the bridges over the Adour impassable. The centre of the allies being now in force on the Bidouse, and concentrating on Sauveterre, the French marshal retired from Bayonne, leaving a powerful garrison behind him for the protection of that important city. The citadel of Bayonne is a truly formidable work, standing on a commanding hill upon the right bank of the Adour, and greatly elevated above all the other defences of the city, nearly fronting the mouth of the Nive. It is almost a perfect square, with strongly-built oreillon bastions at the four angles. A double range of barracks and magazines inclose a quadrangular space in the centre called the _place d’armes_, the sides of which are parallel with the curtains of the citadel. The north-east, north-west, and south-west bastions are surmounted by cavaliers which appear to be well armed with cannon mounted _en barbette_. All necessary preparations for the passage of the Adour had been completed, and from the co-operation of the British navy much assistance was expected. That hope was fully realised; and the noble exertions of the British sailors on the eastern coast of Spain, at St. Sebastian, and at Passages, were crowned by the intrepidity with which the bar of the Adour was crossed. Undaunted by the failure of the leading vessels, which perished in the surf, with death before their eyes, and their comrades swamping in the waters, on came the succeeding _chasse-marées_. At last the true channel was discovered. Vessel succeeded vessel, and before night a perfect bridge was established over the Adour, able from its solidity to resist a river current, and protected from any effort of the enemy by a line of booms and spars, which stretched across the river as a security against fire ships, or any other means which the French might employ for its destruction. Before the flotilla had entered the Adour, or the pontoons had arrived from Bedart, the guards attempted a passage of the river by means of the small boats and a temporary raft formed of a few pontoons, and worked as a flying bridge, by means of a hawser extended from the opposite bank. As the strength of the tide interrupted this precarious mode of passage, when only six companies, with two of the 60th rifles, and a party of the rocket corps, had crossed, the position of this small body, isolated as it was, and open to the attack of overwhelming numbers, was dangerous in the extreme. Colonel Stopford, however, made the best dispositions in his power for defence, and formed with one flank upon the river, and the other appuied upon a morass, while the heavy guns that had been placed in battery on the other shore, swept the ground in front of the position with their fire.