How Many Men Went to War? Population & Armed Forces Sizes in World War One

While World War One might not have been the bloodiest conflict ever by the time it finished in November 1918, but it certainly involved the most direct combatants. The exploding population of Europe meant there was a vast resource of manpower at a nation’s disposal, and incredible number of men served their armed forces.

In Germany, who fought on two fronts for over four years, 20% of the entire population was involved in active service at some point – this means if you were a man of combat age (16-50) it was more likely you would have witnessed the conflict first hand than not. We’ve created a couple of graphs to show the differences in population size, manpower and mobilisation from each belligerent (with British Empire countries showing their individual data).

Total Population and Mobilisation by Country

The Great Powers are highlighted – you can click the top options to change the graphs:

Germany is often perceived as the most militarized country in Europe in 1914, but the graph above suggests differently – Russia clearly had the largest army. Additionally, given that the population of France was 36 million in 1914 to Germany’s 67 million, their relative parity in army size (3,781,000 to 4,500,000) suggests that France was in fact a more militarized nation. In peacetime the French armed forces contained 2.02% of the population to Germany’s 1.31%.

This disparity was recognised at the time – Helmuth Von Moltke told his opposite number Baron Franz Conrad von Hötzendorf in May 1914 that ‘We do not have superiority over the French.’  The illusion of German militarism is most likely the British obsession with Germany’s military, compounded by the Kaiser’s belligerent rhetoric, that underpinned the pre-war arms race.

The data also illustrates the massive discrepancy between the amassed forces of either side. The Russian and French armies had a total peacetime strength in 1913–14 of 2,170,000, compared with a combined German and Austrian strength of 1,242,000: a discrepancy of 928,000. Given the Central Powers only had 57% of the peacetime military strength of France and Russia, and a significantly smaller combined population, it’s quite remarkable that they managed to draw the war out for four years, particularly given Great Britain was also involved.

Great Britain & the Empire

Some historians have put forward that ‘Great Britain won the war’. Certainly, by late 1918 they were a very efficient fighting machine, but they also had an enormous amount of manpower to rely on.  While Great Britain herself ended the war with the 3rd largest military, the addition of men from India, Canada, Australia, New Zealand and South Africa to its ranks meant that it had the largest of all the belligerents. It couldn’t be further from ‘The small contemptible army’ as the Kaiser referred to it in 1914.

James Carson graduated from the University of York with a degree in English and History and have a keen interested in both World Wars and popular science - particularly space.