Siege of Bouchain The Siege of Bouchain ( 9 August – 12 September 1711 ) , following the Passage of the Lines of " Ne Plus Ultra " ( 5 August 1711 ) , was a siege of the War of the Spanish Succession , and the last major victory of John Churchill , 1st Duke of Marlborough . Marlborough broke through the French defensive lines and took Bouchain after a siege of 34 days . Its capture left Cambrai the only French - held fortress between the allied army and Paris . Prelude . Throughout the early summer of 1711 Marlborough ' s army , having taken the important fortress of Douai the previous year , manoeuvred indecisively in northern France , blocked by the French Lines of Ne Plus Ultra – a massive series of fieldworks stretching from the Channel coast to the Ardennes at Namur . The allied army had been weakened by the withdrawal of Prince Eugene ' s army to cover the upper Rhine , as the deposed Elector of Bavaria attempted to take advantage of the disruption caused by the death of the Emperor Joseph . On 6 July , Marlborough captured the small fortress of Arleux , just to the north of the Lines , west of Bouchain , both to deny its use to the French as a sally - port , and to secure the water supply to Douai , which could be cut off by damming the canal that supplied the town . The Duke was then wrong - footed by Villars as the French army crossed the Lines on 22 / 23 July and retook Arleux , with the allied army too far to the west to intervene in time , and the defences were levelled before the French retreated back across the Lines . Marlborough , initially furious , soon retook the initiative by marching his army as if to assault the Lines near Arras , and carrying out a detailed personal reconnaissance there on 4 August in full view of Villars ' covering army . That night the army struck camp , leaving their campfires burning to deceive the French , and marched eastwards to Arleux . At midnight a force from Douai under Cadogan crossed the unguarded French lines , and by 8 am the advance guard of the main army was also crossing over . Villars , arriving on the scene with a few hundred cavalry , realised he had been outmanoeuvred , and though he attempted to offer battle in front of Bourlon Wood , Marlborough declined to attack , the Marshal ' s position being even stronger than the one in which he had given Marlborough ' s army such a mauling two years earlier at Malplaquet . He thus drew off and attempted to hinder Marlborough ' s siege of Bouchain which followed . The Siege . To defend the town Bouchain ' s governor , de Ravignau , had some 5 , 000 men against Marlborough ' s besieging army of 30 , 000 , and the advantage of one of the strongest fortresses left to France , surrounded by the marshy land of the confluence of the rivers Scheldt and Sensée . In addition , Villars ' strong army had taken up position to the west of the allied camp , and had managed to open a tenuous link to the besieged garrison . Marlborough responded by using earthwork gun batteries to counter Villars , used a crack assault force managed by 18 August to once more cut the Marshal ' s communication with Bouchain , and established a fieldwork - protected corridor from the siege camp to his main supply port at Marchiennes on the Scarpe . Frequent raids by Villars on both the supply convoys on the Scarpe , and towards Douai , failed to interrupt the siege , and the garrison marched out to become prisoners of war on 13 September 1711 . Aftermath . Bouchain was Marlborough ' s last campaign . On the last day of the year he was stripped of his position as Captain - General , and of all his other offices . Command of the army on the continent for the campaign of 1712 was given to the Duke of Ormonde , and strict limitations were placed on his freedom of movement . Particularly he was prohibited from engaging the French in battle , as Anglo - French peace talks were well advanced , and the opportunity of seizing Cambrai and marching on Paris , opened by Marlborough ' s gains the year before , was abandoned . Before the year was out , the British army would withdraw from the alliance , leaving the remaining allies , under Eugene of Savoy to be defeated at Denain . Bibliography . Chandler , D . G . : " Marlborough as Military Commander " , ( Spellmount , Staplehurst , 2003 ) < br > Hussey , J . : " Marlborough : Hero of Blenheim " , ( Weidenfeld & Nicolson , London , 2004 )