The Siege of Antwerp was a battle fought on the Western Front of World War I between the German Imperial Army and the Entente forces of Great Britain and Belgium. The Germans besieged the Belgian army and the British Royal Naval Division in the Antwerp area, after the German invasion of Belgium. With no hope of holding Antwerp, the Belgian army withdrew towards the Yser river. In the Battle of the Yser, close to the French border, the Belgians held out against the German onslaught and defended the last part of unoccupied Belgium. The Belgians held the area until late 1918, when they participated in the liberation of Belgium.
By this point, what was left of the Belgian army was at Antwerp: a force of six divisions and eighty-seven battalions of artillery. This was much more than a garrison: it was a force large enough to make the threat of Antwerp as a port quite real. The Belgians conducted three separate offensive operations out of Antwerp. And, as the siege progressed, Antwerp received reinforcements: British marines and French naval troops. General Hans von Beseler, who had the task of taking Antwerp, had only been given about eighty-five thousand men to do it with. Not only was he outnumbered, but his forces were hardly first-line troops.
The Belgian government appealed to France and Britain for direct support. Joffre's response to Belgium's appeal was half-hearted. He refused to release anything more than a scratch force. Furthermore, their task as he saw it was to cover the Belgian army's retreat into France, so that it could join the main operations and extend his left wing. While the British were urging the Belgians to prolong Antwerp's defence, Joffre was simultaneously using his emissaries to persuade them to abandon it. In the event, Britain's direct contribution to Antwerp's defence was limited.
The Antwerp forts had not been built to withstand the shells the German and Austrian heavy weapons were firing. Fort de Wavre fell, and from then on the fortifications surrendered at the rate of one or two a day. Von Beseler was full of plans to speed things up by more aggressive attacks, but he didn’t have the men, and the German General Staff wouldn’t give them to him. Despite French and British reinforcements, the garrison could not hold and had to withdraw. Five days of infantry attacks and bombardment by super-heavy siege artillery were enough to breach the outer ring of forts.
German attacks drove the Entente out of most of the little that was still left of independent Belgium. The greater part of the Belgian Field Army duly carried out a further retirement to the Nieuport-Dixmude line along the River Yser. The front line was held in a costly defensive battle. Victory at the Yser allowed the Belgian Army to maintain control of a small portion of its territory, while the Germans controlled 95% of Belgium.