During the siege, the German armies in the north could use only the single-track line from Trier to Liège, Brussels, Valenciennes and Cambrai, which could accommodate a maximum of forty trains a day.

At the end of August the garrison made several sorties but the third was a costly failure, after which the French prepared to receive the German attack.

Brigadier-General Joseph Fournier, the governor of Maubeuge, surrendered to General Hans von Zwehl on 7 September, effective at noon the next day.

After the Franco-Prussian War of 1870–1871 the French built more fortresses on the German border and extended the frontier fortifications northwards with new building at Hirson, Maubeuge, Lille and Dunkirk.

[3] In three weeks, 1.5 million pickets were driven into the ground for thousands of kilometres of barbed wire, covering 250 acres (100 ha) around the fortifications and intervals.

[3][5] After enjoying a trade boom created by the arrival of army reservists, the morale of civilians in Maubeuge slumped further when they heard of German atrocities from Belgian refugees.

[3] On 12 August, Field Marshal Lord Kitchener had predicted a German offensive through Belgium but sent the British Expeditionary Force (BEF) to Maubeuge as planned.

The BEF began to advance northwards from Maubeuge towards Mons, despite reports from aircrew that a column of German troops "stretched through Louvain as far as the eye could see".

[8] At Maubeuge, news arrived of the fall of most of the Fortified Position of Namur in Belgium and placards put up on the town walls ordering preparations for a siege began an exodus of 25,000 civilians.

British aircraft arrived on 22 August and the passage of a Scottish regiment raised civilian morale briefly, only to be dashed by reports that German troops had crossed the Sambre at Charleroi.

On 25 August, the garrison reserve advanced towards Quévy and Havay over the Belgian border and engineers cut the narrow-gauge railway along the frontier.

On 26 August, the 145th Infantry Regiment, two batteries of 75 mm field guns and a cavalry squadron sortied towards La Longueville to reconnoitre German forces that had been reported there.

Skirmishing took place with German patrols and late in the afternoon the rumble of artillery was heard to the west, which raised hopes that the siege would be lifted but after two days the sounds died away.

[3] By 27 August, Maubeuge had been surrounded and the fortress artillery began speculative bombardments on crossroads and other likely targets, which had little effect beyond revealing the positions of the guns to German observers.

On 28 August, the garrison reserve sallied towards the south and an inconclusive skirmish was fought beyond bois Leroy, which prevented the French from reconnoitring German positions.

Ouvrages were damaged and the occupants risked asphyxiation from gases released by the shell explosions; Fort de Boussois was demolished and the roof of the Menon turret was blown off.

The interval positions were destroyed and an ammunition dump was hit by an Austrian 305 mm shell; the walls collapsed and sixty French troops were asphyxiated.

Fournier ordered that two Territorial battalions were to cover the flanks of the general reserve, one facing Villers Sire Nicole and the other south of the Sambre towards Ferme Watissart.

The commander of the reserve passed on the orders from Fournier but neglected to nominate an axis of advance, which led to uncoordinated attacks and in the rush there was insufficient liaison between the infantry and the fortress artillery.

[3] The 31st Colonial Infantry Regiment advanced quickly into a deluge of artillery and machine-gun fire and reached the fringe of Vieux Reng.

The batteries of the fortress reserve and those at Épinettes were ordered south of Élesmes to defend the support line but lack of transport meant that the artillery was not moved in time.

With the defensive perimeter breached, Fournier called a council of war that evening for opinion on whether to fight to the end at Maubeuge or to attempt a break-out towards Quesnoy and Arras.

Motte managed to hold the line of the Solre stream, with the left flank resting on the Sambre and the right on Ouvrage de Ferrière la Petite.

Fournier refused to contemplate surrender and sent orders to Ville that the remaining defenders were to retire during the night to a position from the Maubeuge walls at Faubourg St Guillain, north-west to Fort de Leveau.

South of the Sambre, Austrian 305 mm howitzers bombarded Ouvrage de Ferriére la Petite and Fort du Bourdiau from behind, quickly making them untenable and endangering the right flank of the line behind the Solre.

Fournier realised that Maubeuge was doomed and that an attempt to delay the Germans on the south side of the Sambre would quickly be forced back on the village of Hautmont, which was thronged with thousands of refugees.

While Grenier had been on his way to Zwehl, Fournier had raised a white flag on the Maubeuge church tower and Brigadier Rene de PeyreCave had the signal repeated in the first sector.

General Neuhaus and a party of German cavalry attempted to take Ville prisoner but he objected because Fournier was still negotiating, as could be seen by the white flag over Maubeuge.

Soon afterwards a German parlementaire took Ville to General Andreas von Harbou at Fort de Laveau where he was shown twelve 77 mm field guns and given a ten-minute ultimatum they would open fire unless he surrendered.

[18] The ration strength of the garrison and support services was 1,000 officers and 48,000 men, including 33,000 infantry (22,000 Territorial) with enough supplies for a siege of at least three months.