"On August 4th, the German troops crossed the Belgian border to score a series of brilliant triumphs. Many in Berlin were confident of a quick victory. The Deutsches Heer appeared to be unstoppable, but it had not counted on Belgium’s will to resist and British intervention."
On August 4th, the German divisions of Otto von Emmich, commander of the Army of the Meuse, violated the Belgian border to open a passage through the Meuse valley and break into the plains to the north of the Ardennes, thus flanking the French armies. The city of Liege, with its twelve forts (http://www.arsbellica.it/pagine/battaglie_in_sintesi/Liegi.html), was the only major obstacle to the advance of von Emmich’s troops. The first fortifications were hit on August 5th. A German brigade managed to penetrate between some forts and occupy the city. However, the bulk of the fortifications continued to resist, inflicting severe losses on the enemy. The garrisons managed to stand up to the besiegers until August 16th, when the arrival of 420 mm mortars enabled the Germans to overcome the defenders. The appearance of heavy artillery with its devastating effects represented the first major news of the war.
The battle of the borders began with the fall of Liege. Finding it impossible to defend Brussels, the Belgian army retired behind the forts of Namur and Antwerp. On August 20th, the German troops occupied the Belgian capital, and on the same day the siege of Namur began, lasting until the 25th. The allied troops on both right and left wings ceded to German superiority. In Lorraine, the French offensive was halted by the German defences. As they were seen as a threat in the north, the High Command sent French troops to the aid of the exhausted Belgians. However, they were severely beaten in Charleroi and the Ardennes.
Despite the German army’s victories, their marching timetable suffered delays that enabled the British expeditionary force (BEF) to take position and rally on the continent. Initially intended to support the French offensive in Alsace and Lorraine, the BEF was diverted in Belgium, undergoing its baptism of fire at Mons on August 24th, where 70 thousand British faced about 150 thousand Germans. The harsh resistance of the British professional soldiers inflicted severe losses on their adversaries, allowing the bulk of the French army to retreat toward the defensive line on the Marne. This first clash confirmed that, in the long term, English training could not overcome the higher number of German troops.
In fact, in the event of war, the original British plans foresaw intensive use of the navy ; they intended to send an expeditionary corps of 100 thousand men as an attachment to the French army in Alsace and Lorraine. British troops, then, would play a supporting role to the larger French army. This approach suffered from the Europeanisation of the British armed forces during the early 1900s. Britain traditionally had a small, well-trained army, which was being increased from 80 to 160 thousand active members, in addition to almost 300 thousand assigned to the Territorial Army (the reserve). However, this represented a limited threat if employed in the same way as the French and German conscripted armies, which boasted much higher numbers. Thus, due to the process of Europeanisation, although the army was aligned qualitatively with the best European troops, it remained quantitatively small.
The considerable influence of the French military, with its great emphasis on the cult of the offensive and the aggressiveness of the soldier (élan), forced British commanders to abandon their troops’ traditional mobility ensured by the Royal Navy, and decide on a more continental approach to war. This situation was indicated in Lord Roberts’ proposal submitted to the war council in the early days of the conflict, in which the Royal Marines would land in Belgium, flanking the front of German attack. The council rejected the proposal because Great Britain had now committed to supporting the French attack along the German border. The new Commander-in-Chief, Lord Kitchener, however, had understood that the conflict would last for years, requiring more than 100,000 active troops. The so-called Kitchener's army was thus launched, providing for the formation of 70 divisions on a voluntary basis. In the early days of the conflict, there was great enthusiasm and euphoria for the war, with long queues to recruitment offices. However, the basis for this phenomenon was Lord Stanley’s so-called Derby Scheme. This foresaw the voluntary registration of the able-bodied on army recruitment lists, and their mobilisation only if deemed necessary. The system had great success in September '14, when more than 460 thousand volunteers flocked in. A crisis in the Derby Scheme began in 1916, with registrations dropping to zero volunteers in July 1917. As a result, the Military Service Act of 1916 introduced obligatory conscription. With an unprecedented effort and a mixture of volunteers and conscripts, the British army grew from 80 thousand men in May 1914 to almost five million active troops in 1918.