Massacre at Mons

In the hands of a trained soldier, the British Short, Magazine-Loaded Lee-Enfield was easily capable of 15 rpm of accurate fire. In the 1930s, a Small Arms School Corps Warrant Officer managed a rate of 37 rpm. This fast rate of fire proved significant in World War I.
Britain declared war on 4 August 1914 and when, by mid-August, the Belgians had been mauled by the German Army, only one intact force stood in the way of the Germans: the British Expeditionary Force (BEF). The first shots fired on 23 August by the BEF were at Malplaquet. The advancing German infantrymen were pulled up short near Mons as the withering rifle fire of the British caused them heavy casualties.
Two days later at Le Cateau the story of Mons was repeated, only on a bloodier scale. Once again the Germans attacked in tightly bunched waves and again they were met with rifle fire so intense that they thought the British were equipped with machine guns.