Background Capture of Gibraltar

at start of war of spanish succession portugal nominally ally of bourbons: france under louis xiv, , spain under grandson, philip v. although not belligerent, portugal s harbours closed enemies of bourbon powers – principally vessels of england , dutch republic. however, following anglo-dutch naval victory @ vigo bay in 1702 balance of naval forces had swung in favour of grand alliance. having ability cut off portugal s food supplies , trade (particularly gold brazil) not hard allied diplomats induce king peter ii sign methuen treaties of may 1703 , join alliance. once peter ii had committed himself war alliance fleets gained access portugal s harbours, in particular port of lisbon. in return allegiance peter ii had demanded military , financial aid , territorial concessions in spain; had asked alliance send lisbon emperor leopold s younger son, charles – alliance s habsburg candidate spanish throne – demonstrate earnestness of support. known supporters charles iii of spain, young pretender arrived in lisbon – via london – george rooke s fleet on 7 march 1704, amid great celebrations.

apart failed grand alliance attempt take cádiz in 1702, , subsequent attack on spanish treasure fleet in vigo bay, war had far been limited low countries , italy. portugal s change of allegiance, however, war moved towards spain. in may 1704 court @ lisbon received news french , spanish troops had crossed frontier portugal. army of approximately 26,000 men under philip v , duke of berwick scored several victories on border: salvaterra fell on 8 may, penha garcia on 11 may, philip v oversaw fall of castelo branco on 23 may, , t serclaes captured portalegre on 8 june. without supply forces, coming summer heat made impossible them continue campaign, , philip v returned madrid on 16 july hero s welcome. however, heat did not affect war @ sea alliance in position of strength.