The Croisière de Bruix (or Bruix' expedition of 1799) was the principal naval campaign of the year 1799 during the French Revolutionary Wars. The expedition began in April 1799 when the bulk of the French Atlantic Fleet under Vice-Admiral Étienne Eustache Bruix departed the base at Brest, evading the British Channel Fleet which was blockading the port and tricking the commander Admiral Lord Bridport into believing their true destination was Ireland. Passing southwards, the French fleet narrowly missed joining with an allied Spanish Navy squadron at Ferrol and was prevented by an easterly gale from uniting with the main Spanish fleet at Cádiz before entering the Mediterranean Sea. The Mediterranean was under British control following the destruction of the French Mediterranean Fleet at the Battle of the Nile in August 1798, and a British fleet nominally under Admiral Earl St Vincent was stationed there. Due however to St. Vincent's ill-health, operational control rested with Vice-Admiral Lord Keith. As Keith sought to chase down the French, the Spanish fleet followed Bruix into the Mediterranean before being badly damaged in a gale and sheltering in Cartagena.
Bruix successfully evaded Keith's pursuit, briefly putting in at Toulon and then operating off the Italian coast in June. Keith belatedly followed Bruix' trail, his progress obstructed by distant orders from St Vincent and disobedience from Vice-Admiral Lord Nelson who commanded a separate squadron at Palermo and refused to participate in the campaign due to his preoccupation with the political situation in Naples. By the time Keith reached Toulon the French admiral had sailed westwards once more, joining with the Spanish force at Cartagena to form a fleet of 40 ships of the line. In early July, unaware that Bruix had returned through the Straits of Gibraltar to the Atlantic, Keith was joined by a heavy reinforcement sent by Bridport and reprovisioned his force at Port Mahon and Gibraltar before renewing the chase. During late July and early August Keith pursued Bruix into the Atlantic and rapidly closed the gap between the fleets as they crossed the Bay of Biscay. Ultimately however Bruix reached Brest on 13 August, just one day ahead of Keith, unopposed by the remainder of Bridport's fleet which was stationed off Rochefort blockading a Spanish squadron from Ferrol anchored there.