The Second Battle of Algeciras (also known as the Battle of the Gut of Gibraltar) was fought on 12 July 1801 between a Royal Navy squadron and a larger Spanish and French squadron in the Gut of Gibraltar during the Algeciras campaign of the war of the Second Coalition. The battle followed the First Battle of Algeciras on 6 July, in which a French squadron anchored at the Spanish port of Algeciras was attacked by a larger British squadron based at nearby Gibraltar. In a heavy engagement fought in calm weather in the close confines of Algeciras Bay, the British force had been becalmed and battered, suffering heavy casualties and losing the 74-gun ship HMS Hannibal. Retiring for repairs, both sides called up reinforcements, the French receiving support first, from the Spanish fleet based at Cádiz, which sent six ships of the line to escort the French squadron to safety.
Arriving at Algeciras on 9 July, the combined squadron was ready to sail again on 12 July, departing Algeciras to the westwards during the evening. The British squadron under Rear-Admiral Sir James Saumarez, having effected its own hasty repairs, set off in pursuit. Finding that his ships were falling behind, Saumarez instructed his captains to separate and attack the combined squadron as best they were able to. The fastest ship was HMS Superb under Captain Richard Goodwin Keats, which sailed through the Spanish rearguard as a moonless night fell. Superb fired on the rearmost ships, setting the 112-gun Real Carlos on fire and capturing the Saint Antoine. Unable to determine friend from foe in the darkness, Real Carlos inadvertently engaged the Spanish ship San Hermenegildo, spreading the fire to its compatriot. Both ships subsequently exploded with enormous loss of life. A second stage of the battle then developed, as HMS Venerable took the lead of the British line, attacking the rearmost French ship Formidable under Captain Amable Troude. In a furious and protracted engagement, Venerable suffered heavy damage and was driven ashore, allowing the remainder of the French force to return to Cádiz without further fighting.
After the battle, Venerable was towed back to Gibraltar for repairs, while the rest of the British squadron resumed the blockade of the French and Spanish ships in Cádiz, returning the situation to that before the battle. This British victory, coming so soon after Saumarez's defeat in Algeciras harbour, did much to restore parity in the region and the heavy casualties inflicted on the Spanish contributed to a weakening of the Franco-Spanish alliance and the signing of the Treaty of Amiens, which brought the war to a temporary halt early the following year. In France, despite the heavy Spanish losses, the battle was celebrated as a victory, with Troude widely praised and promoted for the defence of his ship.
In August 1798, the French Mediterranean Fleet was largely destroyed by a British fleet at the Battle of the Nile during the French invasion of Egypt. With the Royal Navy dominant in the Mediterranean Sea and their army trapped in Egypt, the French sought in 1801 to augment their depleted forces in the region by sending reinforcements from the Atlantic Fleet and by purchasing ships from the Spanish Navy, based in Cádiz. A squadron sailed from Brest on the Atlantic in January and made three failed attempts to reach Egypt, which was facing a large British invasion, before abandoning the effort and retiring to Toulon on the French Mediterranean coast. Three ships of the line, Formidable, Indomptable and Desaix, had been detached from the squadron in May however and were subsequently placed under the command of Contre-Admiral Charles Linois under orders to sail for Cádiz. At Cádiz, the Spanish fleet had agreed to sell six ships of the line to the French Navy, and on 13 June two French frigates, Libre and Indienne, arrived at the port to oversee the transfer under the command of Contre-Admiral Dumanoir le Pelley.
En route to Cádiz, Linois had learned from the crew of the captured brig HMS Speedy that a powerful British squadron of seven ships of the line under Rear-Admiral Sir James Saumarez lay off Cádiz, blockading the port. Concerned that this squadron could overwhelm his own, Linois took shelter in the small but well-defended harbour of Algeciras, just across Algeciras Bay from the heavily fortified British naval base at Gibraltar. Saumarez was informed of Linois's arrival, and turned eastwards to confront him, discovering the French ships anchored in a well prepared position on the morning of 6 July. Saumarez attacked immediately, but found that his ships were hampered by a lack of wind. Becalmed under heavy fire, the British squadron inflicted severe damage on the French ships which withdrew into shallower water, two grounding. However, when Saumarez ordered his ships to follow, HMS Hannibal grounded as well, trapped under a heavy barrage from the shore. With no wind with which to manoeuvre and the squadron's boats all either sunk or engaged in towing the battered HMS Pompée back to Gibraltar, Saumarez called off the attack at 13:35. The battered British squadron retired to Gibraltar, except for Hannibal, which was trapped, battered and swiftly forced to surrender, having lost two masts and more than 140 men.
With both squadrons badly damaged, reinforcements were called for, Linois sending a messenger overland to Cádiz with an appeal for the Spanish fleet there, under Admiral Jose de Mazarredo y Salazar to send a squadron to escort the French force in Algeciras to the safety of Cádiz. At Cádiz, le Pelley had to plead with Mazzaredo for assistance, the Spanish admiral agreeing on 8 July to send a powerful squadron under Vice-Admiral Juan Joaquín Moreno de Mondragón to Algeciras. Moreno's force consisted of two 112-gun first rate ships of the line, Real Carlos and San Hermenegildo, the 96-gun San Fernando, 80-gun Argonauta and the 74-gun San Agustín. With this force was the 74-gun French ship Saint Antoine, which a few days earlier had been the Spanish San Antonio. Saint Antoine was the first of the French ships purchased from the Spanish Navy to enter service, the crew drawn from the crews of le Pelley's frigates supplemented by Spanish sailors and commanded by Commodore Julien le Ray. With the squadron were the frigates Libre, Indienne and the Spanish Sabina as well as the French lugger Vautour.
The combined squadron sailed from Cádiz on 9 July, progressing rapidly southwards and reaching Algeciras Bay late in the afternoon, except for Saint Antoine which was delayed and arrived the following morning. The force was anchored close to Algeciras, well out of range of cannon at Gibraltar, and there waited for Linois to finish making the necessary repairs to his ships. Shadowing the combined squadron was a small British force under Captain Richard Goodwin Keats on HMS Superb with the frigate HMS Thames and the brig HMS Pasley. Although part of Saumarez's squadron, Keats had been too late to take part in the first battle, and had instead cruised off Cádiz watching the Spanish fleet there. When Moreno sailed, Keats was initially chased by portions of the Franco-Spanish squadron, but eluded and followed them, subsequently joining Saumarez at Gibraltar. At the British port, the dockyards were the scene of frantic activity as Saumarez, supported by commissioner Captain Alexander Ball, sought to repair his squadron so that it could intercept Moreno's forces on their voyage back to Cádiz. Pompée was temporarily abandoned in the yard, her crew redistributed to work on the rest of the squadron. Saumarez also gave orders that his flagship, HMS Caesar, was also to be left at Gibraltar, but Captain Jahleel Brenton requested the opportunity to repair his ship and Saumarez relented, the crew of Caesar working all day and in shifts throughout the night in order to bring their ship up to fighting standard. Saumarez believed however that due to the condition of Linois's ships and the mistaken assumption that the combined squadron would sail for Cartagena to the east, he would have at least two weeks to prepare and sent messages to the Mediterranean Fleet under Lord Keith, then at sea off Egypt, requesting support against the combined squadron.