From Wikipedia

 South Africa: The Boer War

The Boer War also had another significance. The Army Medical Corps discovered that 40% of men called up for duty were physically unfit to fight. This was the first time in which the government was forced to take notice of how unfit the British Army was and this severe lack of physically-trained armed forces strengthened the call for the Liberal Reforms of the first decade of the twentieth century. Thus this was one of the prime reasons for the subsequent introduction of compulsory games and at least one hot meal in British schools.