At the outbreak of war in 1914, the British Expeditionary Force sent to France, although comparatively small was probably one of the best trained armies Britain had ever fielded at that point. It was a purely volunteer force and therefore highly motivated, and due to Britain's Empire across the globe at that time, experienced. When it finally encountered the invading German armies in the first major clash at Mons, the British Army attempted to hold the line of the Mons–Condé Canal against the advancing German 1st Army. Although the British fought well and inflicted disproportionate casualties on the numerically superior Germans, they were eventually forced to retreat due both to the greater strength of the Germans and the sudden retreat of the French Fifth Army, which exposed the British right flank. Though initially planned as a simple tactical withdrawal and executed in good order, the British retreat from Mons lasted for two weeks and took the BEF to the outskirts of Paris before it counter-attacked in concert with the French, at the Battle of the Marne.
This range of figures covers the troops that fought in the first 2 years of the war and can also be used in the Irish Wars of Independence and the imaginary Very British Civil War (VBCW).