The war began with a massive and unprecedented wave of enthusiasm. At the start of August 1914 Parliament had issued a call for an extra 500,000 soldiers and the response was overwhelming. By the end of September over 750,000 men had enlisted, by January 1915 a million. The desire to join and fight was genuine, enthusiastic and showed "almost mystical patriotism". Pre-war tensions in Ireland were swept aside, men from the UVF and Catholics both rushing to join, Ulster providing twelve battalions in the first months. The patriotism was classless, the prestigious universities and public schools provided 30,000 officers from their OTCs immediately and many more officers subsequently. Sixth forms and universities were almost emptied as the war continued.
One early peculiarity was the formation of 'Pals' battalions, groups of men from the same factory, football team, bank and similar joining and fighting together, first suggested at a public meeting by Lord Derby within three days he oversaw volunteers sufficient for three battalions. Kitchener, the Minister of War, gave official approval for the measure almost instantly and the response was impressive, Manchester raised fifteen specific 'Pals' battalions and all the way down to Accrington, Lancashire which raised one. The drawback of 'Pals' batallions was that a whole town could lose its military-aged menfolk in a single day.
The government demand for men continued unabated, after the first call in August for 500,000 men a further 3.5 million were called for before the year's end. The pre-war calculations had supposed that the British Expeditionary Force would lose around 40% of its manpower in the first six months of fighting, Kitchener's predictions of three years fighting and a million men needed being regarded as incredible. The seven divisions of the BEF, totalling 85,000 men, had been landed in France at the outbreak of war, casualties in the first three months totalled almost 90,000. By mid-1915 this total had risen to around 375,000 men even before the autumn offensives and the rate of recruitment was falling off, for a number of reasons.
In 1914 the total available number of men of military age was 5.5 million, with around 500,000 more reaching the age each year. By late September 2.25 million men had been enlisted and 1.5 million were in reserved occupations. Of the rest the recruiters had uncovered a dismaying fact - almost two in every five volunteers were entirely unsuitable for military service on the grounds of health. When volunteer numbers fell to around 70,000 a month after the Dardanelles Expedition the government felt forced to intervene, although they initially avoided conscription. A National Registration Act created a register that revealed the number of men still available and they were targeted in a number of ways. The skills of advertising were brought to bear with posters, public meetings, tales of German atrocities, and the threat of shame. The 'Derby Scheme' used door-to-door visits to gather men to 'attest' to serve if needed.
With insufficient numbers attesting and the French Army in dire need of relief a Military Service Bill was introduced in January 1916, providing for the conscription of single men. In May the conscription was made universal, although Ireland was excluded from the scheme and the government pledged to not send teenagers to serve in the front line. However this had little impact on enlistments, the number continued to decline towards 40,000 a month as essential men were needed for war work and the poor health of many others remained, even as the requirements were progessively reduced. From 1.28 million enlisting in 1915 this had fallen to 1.19 million for 1916 and fell to around 820,000 for 1917. The healthy manpower was simply not there, in 1917-18 only 36% of men examined were suitable for full military duties and 40% were either totally unfit or were classified as unable to undergo physical exertion. In 1918 the British Army was actually smaller than in 1917 (3.84 million to 3.9 million) and almost half the infantry was nineteen or younger.
The idea of conscientious objection had been included in the 1916 bills, with objectors appearing before special local groups to obtain exemption. Around 7,000 men were granted non-combatant duties, while a further 3,000 were sent to special labour camps. Many others who failed to be given an exemption were enlisted and sent to France to potentially face the threat of firing squad. This threat was more real to around 1,000 men who completely refused any form of service, they were forced into the army and forty-one of them were later sentenced to death, reprieved only by the intervention of Lloyd George. During the war, 304 British soldiers were executed for cowardice.