The Belgian garrison had no hope of victory without relief; despite the arrival of the Royal Naval Division beginning on 3 October, the Germans penetrated the outer ring of forts.

On 9 October, the remaining garrison surrendered, the Germans occupied the city and some British and Belgian troops escaped to the Netherlands further north to be interned for the duration of the war.

[a] The city of Antwerp (military governor general, Victor Deguise) was defended by numerous forts and other defensive positions and was considered to be impregnable.

Since the 1880s, Belgian defence planning had been based on holding barrier forts on the Meuse (Maas) at Liège and at the confluence of the Meuse and the Sambre rivers at Namur, to prevent French or German armies from crossing the river, with the option of a retreat to the national redoubt at Antwerp, as a last resort, until the European powers guaranteeing Belgian neutrality could intervene.

By 17 August, a huge number of German troops had crossed into Belgium between the Meuse, Demer and Gete, despite the demolitions carried out by the Belgian Army and paramilitary Garde Civique.

[8][9] The Belgian government of Charles de Broqueville left Brussels and moved to Antwerp to avoid capture by the Germans, who detached the III Reserve Corps from the First Army to mask the city from positions either side of the Dyle Canal.

The 6th and 5th reserve, marine and 4th Ersatz divisions forced Belgian outposts back 4–5 mi (6.4–8.0 km) on 28 September and formed a covering line from the Nete to the Scheldt at Mechelen.

Behind the covering line, German siege artillery was installed to the east and south of Mechelen, ready to commence a bombardment on Forts Sint-Katelijne-Waver and Walem as the Dorpveld and Bosbeek redoubts, to the north-east of Sint-Katelijne-Waver were engaged by 8 in (200 mm) mortars and the field defences between the forts, the Nete bridges and Antwerp waterworks north of Walem were bombarded by other heavy guns.

[13][b] Work by Belgian engineers to construct field defences around Antwerp had gone on since the beginning of the war, building positions in the intervals between the forts, inundations formed and the foreground cleared of obstructions.

The clearances proved unwise, since they made the forts visible, trenches could only be dug 1 ft (0.30 m) deep, because of the high water-table and had no overhead cover.

[18] On 2 September German intelligence sources in Brussels reported that c. 40,000 British troops had landed at Ostend, occupied the coast westwards to Boulogne and reinforced the Belgian Army in Antwerp.

Landsturm battalions were transferred from the Generalgouverneur appointed to administer occupied Belgium, Field Marshal Von der Goltz and a division of the Marinekorps was ordered to the area.

[23][c] At Antwerp, the German concentration of troops on the south-eastern side of the line had left a gap to the north from the Dender to the Dutch frontier.

The gap spanned about 13 mi (21 km) at the confluence of the Dender and the Scheldt rivers at Dendermonde, through which the defenders of Antwerp retained contact with western Belgium and the Allied forces operating on the coast and in northern France.

[27] Early on 29 September, the Belgian Prime Minister, Charles de Broqueville, informed the British that if all the outer forts were lost, the government and field army of 65,000 men would withdraw to Ostend and leave the 80,000 fortress troops to hold Antwerp for as long as possible.

The Belgian 2nd Division at the east side of the 3rd Sector, began to retire across the Nete at noon and an hour later the 1st Division began to withdraw to an unfinished intermediate position, from Rumst 2 mi (3.2 km) north-west of Fort Walem to Duffel and Lisp, 1 mi (1.6 km) above Lier, which had bridgeheads at Duffel, Anderstad and Lier.

[30] The Duffel redoubt was evacuated on 3 October after the garrison ran out of ammunition and German artillery-fire was switched to Fort Kessel on the flank of the break-in.

Orders for a counter-attack against the German battalions on the north bank were not issued until 1:15 a.m. on 6 October and did not arrive in time to all of the Belgian and British units in the area.

The defenders withdrew to another unfinished position midway between the Nete and the inner forts, from Vremde 5 mi (8.0 km) south-east of the centre of Antwerp, to the Lier–Antwerp road and then south-west around Kontich during the day.

The British forces under the command of Major-General Archibald Paris, were ordered by First Lord of the Admiralty, Winston Churchill, to continue the defence for as long as possible and to be ready to cross to the west bank rather than participate in a surrender.

The width of the escape route from Antwerp had been reduced to fewer than 12 mi (19 km), which led to the Belgian commanders ordering the field army to retreat behind the Terneuzen Canal, which ran from Ghent northwards to the Dutch border.

[38] Fires could not be put out after the waterworks had been hit; rampart gates on the enceinte (main defensive wall) where the wet ditches were bridged were also bombarded.

Erroneous reports to the Belgian and British commanders before dawn on 8 October that forts 1, 2 and 4 had fallen, led to a decision that if they were not recaptured, the inner line would be abandoned at dusk and the defenders withdrawn to the city ramparts.

The ramparts were earth parapets with shelters underneath and had caponiers (passages) protruding on the flanks, with moats 60 yd (55 m) wide and 10–15 ft (3.0–4.6 m) deep in front.

[41] Early on 9 October German troops found some of the forts of the inner ring empty; Beseler had the bombardment stopped and summoned the Military Governor, General Deguise to surrender.

On the morning of 10 October, when the Chief of Staff of the Military Governor appeared with authority to discuss surrender, he was presented with a fait accompli and had to agree to the terms already accepted.

33,000 soldiers of the Antwerp garrison fled north to the Netherlands, where they were interned for the rest of the war, as far as possible from the Belgian border, for fear of compromising Dutch neutrality.

[50][51] The Belgian forces which had escaped from Antwerp had been in action for two months and the King planned to withdraw west of a line from St Omer–Calais to rest the army, incorporate recruits and train replacements but was persuaded to assemble the army on a line from Dixmude, north to the port of Nieuport and Furnes 5 mi (8.0 km) to the south-west of the port to maintain occupation of Belgian territory.

The 4th, 1st and 2nd Divisions prolonged the line north with advanced posts at Beerst, Keyem, Schoore and Mannekensvere, about 1 mi (1.6 km) forward on the east bank.

The German IV Cavalry Corps had moved south four days previously, except for several Uhlan who were disturbed by a party arranging billets and captured by the 10th Hussars.