When the Belgian field army retreated from Liege in August 1914, it fell back on the fortified camp of Antwerp,
the Belgian National Redoubt, to await assistance from either France or Great Britain.
Antwerp, with its triple ring of fortifications spanning a circumference of more than 100 kms was at the time considered an impregnable position. But the Belgian Field Army and Antwerp garrison of altogether some 120 000 to 150 000 men was not strong enough to hold the forts in face of a determined assault, especially
when the assaulting forces were backed by mobile heavy siege aritillery, at the time a technological marvel weapon. Antwerp was the third largest port in the world, but as per treaty with the Netherlands, in time of war the river Scheldt was blocked to all military traffic at Dutch discretion. The river was closed in early August and no British reinforcements could be expected via that route without provoking Dutch entry into the war on the German side. And in any case, neither of the two Entente Powers were able to spare forces until early October, after the Battles of the Marne and the Aisne. By then the British forces sent to Antwerp, some 8000 Naval Brigade troops, were insufficient to hold the line.
Meanwhile, from mid-August onwards, the Belgian field army, government and King remained in the Antwerp fortified camp, conducting several large scale sorties against German positions to the south. This so unmoved the German command that at critical points during the Battle of the Marne, German units were sent north to reinforce the line against Belgian attacks.
By September it was decided to definitively remove the threat posed by the Belgian army. Albert I, King of the Belgians refused German diplomatic offers to take no further part in the fighting in Europe. German forces besieging the line of forts protecting the city were reinforced and heavy German and Austrian siege artillery was brought up. The intention was to take Antwerp and force Belgium out of the war by either capturing or decisively defeating the Belgian army. This had to be done before British and French reinforcements arrived at the besieged city.
The main battle for Antwerp started on September 27. The last fort surrendered on October 10, one day after German forces took possesion of the city. On the whole, the Belgian Army and British forces were able to escape the city to make their way to the Belgian coast. Later events during the Great War far eclipsed the siege and capture of Antwerp in terms of manpower, duration, destruction, loss of life and misery : but at the time the fall of the fortified camp of Antwerp was considered a dramatic event and a grave loss to the cause of the Entente Powers. The Germans made much of the fall of Antwerp, regarding it as a consolation prize for having failed to take Paris the month before; but as military river traffic was forbidden by the Netherlands authorities who held control over the river mouthing, and as other maritime transport was blockaded by the Royal Navy, in the end Antwerp was never turned into the proverbial 'pistol aimed at the heart of England.' Nor did the city play a part in German defensive strategy as planned during the final months of the war in 1918. Plans to turn the great fortress into the northern lynchpin of a German line of defense running along the Nethe and Meuse rivers, were never carried out due to the sudden cessation of hostilities in November 1918.