By the end of 1914—after the battles of Mons, Le Cateau, the Aisne and Ypres—the existent BEF had been almost exhausted, although it helped stop the German advance.

Emperor Wilhelm II of Germany, who was famously dismissive of the BEF, allegedly issued an order on 19 August 1914 to "exterminate ... the treacherous English and walk over General French's contemptible little army".

Under the terms of the Entente Cordiale the United Kingdom had a diplomatic "understanding" with France to counter military aggression from the German Empire in the European continent.

Detailed plans had been made for the British Army in the event of war breaking out between those two countries to dispatch an Expeditionary Force to France which consisted of six infantry divisions and five cavalry brigades under the command of General Sir John French to repel any German attack in the West.

[4] By the end of 1914, after the battles of Mons, Le Cateau, the Aisne and Ypres, the old regular British Army had suffered massive casualties and lost most of its fighting strength but had managed to help stop the German advance.

After Plumer's return from Italy Rawlinson spent a period as British Permanent Military Representative at the Supreme War Council at Versailles, but at the start of April he took over the remnants of Gough's Fifth Army after its recent defeat.

[10] The British held up the German advance until the evening when they began retiring to a second defensive line in the retreat from Mons during which they were engaged in the Battle of Le Cateau.

[11] The Allied retreat finally ended at the River Marne, where Entente forces prepared to make a stand to defend Paris.

Then for a three-week period following the development of trench warfare each side gave up frontal assaults and began trying to encircle each other's flank.

The continuous trench lines of the Western Front now stretched 400 miles (640 km) from the North Sea to the Swiss frontier.

Allied forces attempted to break through the German lines along a 25 miles (40 km) front north and south of the River Somme in northern France.

[19][20] Upon arrival in Marseille on 30 September 1914, only six weeks after the declaration of war, they were moved to the Ypres Salient and took part in the Battle of La Bassée in October 1914.

[19]The Expeditionary Force was hampered by a lack of familiarity with new equipment, only being issued Lee–Enfield rifles on their arrival in France and they had almost no artillery, relying on support from their neighbouring corps when in the front line.

[19] They were not accustomed to the continental weather and were poorly equipped to resist the cold, leading to low morale which was further compounded by the reserve system, whereby reinforcements were drafted in from any regiment and had no affiliation to their new units.

[19] The South African Overseas Expeditionary Force consisted of the 1st South African Infantry Brigade of four infantry battalions supported by five Heavy Artillery batteries, a Field Ambulance, a Royal Engineers Signal Company and a General Hospital[21] under the command of Brigadier General Henry Lukin.

Since they were mostly untouched by the German offensive in the spring of 1918, the Canadians were ordered to help spearhead the last campaigns of the War from the Battle of Amiens in August 1918.

Upon the outbreak of war, New Zealand immediately offered to provide two brigades — one of infantry and one of mounted troops — a total of 8,500 men.

[26] The Australian Imperial Force (AIF) was originally supposed to supply 20,000 men organised into one infantry division and one light horse brigade plus supporting units.

On 4 June, the 1st Infantry Brigade of the 1st Division repelled the first major attack made by the German Army against the lines defended by the CEP troops.

[36] The other officers' weapon was the revolver, the three most common being the Webley MK V or VI, the Colt New Service and the Smith & Wesson hand ejector.

[36] All other ranks in the BEF carried a .303 Lee–Enfield rifle fitted with an easily loaded ten-round magazine and issued with a seventeen-inch (430 mm) bayonet.

These rifles enabled a high rate of fire with good accuracy, such that pre-war British soldiers were trained to hit a target fifteen times a minute at a range of 300 yards.

[37] The devastating efficiency and accuracy of the BEF infantry led the Germans to incorrectly believe that there were approximately 28 machine guns in each battalion.

[38] When the BEF landed in France each infantry battalion and cavalry regiment was equipped with two Vickers or Maxim machine guns.

[36] Part of the reason for only allocating two guns per unit was the cost of manufacture and the need of a ten-week intensive training course for a Vickers gunner.

[36] During the course of 1916, the quicker to manufacture and more versatile Lewis guns began to be issued on the intended scale of the sixteen per battalion, one for each platoon.

[40] The 1914 Star was issued to officers and men of British forces who served in France or Belgium between 5 August and midnight 22/23 November 1914.

To qualify, the recipient had to have been a member of the Territorial Force on or prior to 30 September 1914, and to have served in an operational theatre outside of the United Kingdom between 5 August 1914 and 11 November 1918.

[40] The British Army during the Great War was the largest military force that Britain had ever put into the field up to that point.

The official "final and corrected" casualty figures for the British Army, including the Territorial Force, were issued on 10 March 1921.