Siege of Dunkirk ( 1944 – 45 ) The Siege of Dunkirk in World War II occurred from September 1944 when units of the Second Canadian Division surrounded the heavily fortified city and port of Dunkirk . German units within the fortress withstood initial probing attacks , and as the opening of the port of Antwerp became a higher priority , the Allied commander , Montgomery , decided to merely contain the Germans within Dunkirk without attacking the fortified city . For this task , the 1st Czechoslovak Armoured Brigade was used . The German garrison remained in Dunkirk until the general German surrender in May 1945 . In so doing , the garrison denied the Allies the use of the port . The fortress , commanded by Admiral Friedrich Frisius , eventually surrendered unconditionally to Brigade General Alois Liška , the commander of the Czechoslovak brigade group , on 9 May 1945 . Background . The 1st Canadian Army had been allocated the left of the 21st Army Group ' s line of advance and General Bernard Montgomery , the commander of 21st Army Group , had directed them to clear the Channel Ports before continuing into the Netherlands . Most of these ports , however , had been heavily fortified and , despite the generally poor quality of the garrisons , it was necessary to mount full - scale major assaults . The ports were needed to supply the allied armies and the lack of such facilities had halted or slowed much offensive activity . Montgomery had estimated that the Channel Ports would be sufficient for his needs and this view persisted until mid - September . Under pressure from Dwight Eisenhower , the Allied Supreme Commander , Montgomery modified his instructions to the Canadian commander , Henry Crerar , on 13 – 14 September thus : " Early use of Antwerp so urgent that I am prepared to give up operations against Calais and Dunkirk " and : " Dunkirk will be left to be dealt with later ; for the present it will be merely masked . " Action against Calais continued ( see Operation " Undergo " ) , at least partly due to the need to silence the heavy artillery sited nearby . The forces that might have been used to capture Dunkirk were released to assist on the Scheldt and thus open access to the largely undamaged port of Antwerp . Instead , smaller Allied forces held a perimeter around the city . Forces involved . In the first weeks of the siege , while Allied forces were being deployed on the Scheldt , several units took short turns at containing Dunkirk . The 5th Canadian Infantry Brigade , part of 2nd Canadian Infantry Division , was relieved by the 4th Special Service Brigade ( a Royal Marines Commando formation ) , which was in turn relieved by the 154th Infantry Brigade . However , the bulk of the siege was performed by the 1st Czechoslovak Armoured Brigade from early October until the final surrender . The German garrison consisted of a wide variety of units , including Navy and Air Force personnel , as well as Army and Fortress units . There was also a 2 , 000 strong Waffen - SS detachment . The total strength was in excess of 10 , 000 men . Many of these were remnants of five Army divisions which had been mauled during the Normandy campaign and had retreated to Dunkirk . The town itself was heavily fortified , and well - supplied for a lengthy siege . Opening moves . The Canadians approached Dunkirk from the south west . On 7 – 8 September , the 5th Canadian Infantry Brigade captured Bourbourg , about from the city itself . The German outer perimeter ran through the villages of Mardyck , Loon - Plage , Spycker , Bergues and Bray - Dunes , from from Dunkirk . The Calgary Highlanders attacked Loon - Plage on 7 September against very heavy opposition and suffered enough casualties that each of its companies was reduced to less than 30 men . The village was gained on the 9th only when the Germans withdrew . During the next ten days , Canadian units nibbled away at the German perimeter , taking Coppenaxfort on the 9th , Mardyck on the 17th , both west of the city , Bergues on the 15th and Veurne , Nieuport ( greatly aided by precise intelligence received from the Belgian White Brigade , the national resistance movement ) and De Panne , east of Dunkirk , in Belgium . Bray Dunes and nearby Ghyvelde , both just within France , were taken on 15 September , with air support after initial attacks had failed . It had become clear that the German defenders were not about to be expelled without a major assault . Given the need to open up the Scheldt to Antwerp and the likelihood that Dunkirk would be of limited use as a supply port as a result of its demolition , the major Canadian units were redeployed . Nearby Ostende had fallen easily to the Canadians when the Germans withdrew , and its port was partially opened on 28 September , easing the Allies ' supply problems . Dunkirk was no longer worth the effort of its capture The siege . The Allied forces around Dunkirk were to contain the German garrison and minimise their inclination to fight on by aggressive reconnaissance , artillery and air bombardment and propaganda . Coastal supply routes used by German E - Boats and air supply drops were to be cut off . Of all of the German fortress garrisons on the Channel coast , Dunkirk appears to have been the most resilient . They had thwarted early probes by the Canadians with sufficient aggression to dissuade them from a full assault . By this stage , other priorities had come into play , compelling the ' Canucks ' to persist in aggressive patrolling and successful local counter - attacks . On the night of 26 – 27 September , the Germans attempted to take advantage of the local inexperience of the recently - deployed 154th Brigade . Two serious attacks were mounted , against the 7th Black Watch in Ghyvelde and the 7th Argylls at nearby Bray - Dunes Plage . Both were beaten off , but only after the Argylls ' headquarters had been partially occupied and houses in Ghyvelde had been destroyed . On 4 October , a 36 - hour truce was agreed between the two sides , at the initiative of the French Red Cross , to allow the evacuation of 18 , 000 French civilians and Allied and German wounded . This passed without incident and was even extended to allow the Germans to restore defences that had been removed to allow the evacuation . Once deployed , Czech forces executed frequent raids into Dunkirk ' s eastern suburbs , for nuisance effect and to take prisoners . There was a flurry of attacks and retaliatory counter - attacks , mostly on Dunkirk ' s eastern side , in November 1944 . Conditions for besiegers and besieged were difficult in the winter . The low - lying ground outside the city had been flooded to form part of the defences and adjacent land easily became water - logged , hampering movement and making life unpleasant . Canadian artillerymen reported that gun - pits needed to be bailed out , the sides of dugouts collapsed and transport became mired . This was mitigated by leave in nearby towns and in Lille . The defenders were stuck with poor food , deficient health care and harsh discipline . Surrender . After the general German surrender , the garrison surrendered unconditionally to Alois Liška on 9 May 1945 . Substantial reserves of food and ammunition remained in Dunkirk . Order of battle . German garrison . Elements of the following formations :