From Russia’s Last Gasp: The Eastern Front 1916–17, by Prit Buttar (Osprey, 2016), Kindle Loc. 169-95:
A combination of industrialisation and major improvements in public health in the second half of the 19th century led to large increases in the population of Europe, rising from about 200 million in 1800 to double that figure by 1900. The experiences of war during the 19th century resulted in most large nations adopting systems of national service followed by a variable period as a reservist; as a result, when the continent plunged over the precipice into war in the summer of 1914, all the Great Powers had the ability to field forces on a scale that dwarfed anything that had gone before.
The same industrialisation that helped increase the population of Europe also provided arms and munitions on a scale to match the huge armies that were sent into battle. Yet despite the enormous stockpiling and production of guns, bombs and shells, all armies found themselves struggling to cope with the huge consumption of resources that followed. Every army that fought in 1915 was forced to moderate its military ambitions to live within the limitations imposed by ammunition shortages, and it was only at the end of the year that all sides could begin to look forward to a time when they might have sufficient matériel to cope with the demands of modern warfare.
In the west, the terrible irony of the ‘mobilisation’ of 1914 was that hundreds of thousands of men were left facing each other in almost static front lines, subjecting each other to bombardments and assaults that left huge numbers dead or maimed without any prospect of ending the war. In many respects, the fighting on the Eastern Front was very different, with the front line moving back and forth as the vast spaces of Eastern Europe allowed armies to exploit weaker areas. However, the very space that allowed for such movement also made a conclusive victory almost unachievable. As early as October 1914, the Germans had correctly calculated that it was impossible for armies to maintain operations more than 72 miles (120km) from their railheads, and both sides rapidly realised that there were few if any strategically vital objectives within such a radius. Consequently, although there were major advances by all sides, it was not possible to advance sufficiently far to force the other side out of the war.
The Great Powers entered the war with a clear idea of how they intended to win. Germany wished to avoid a prolonged two-front war, and opted to concentrate most of its strength against France, intending to send its victorious armies east after defeating its western opponents. Russia believed in the irresistible might of its vast armies, and anticipated a steady advance that would roll over the German and Austro-Hungarian forces, while the armies of the Austro-Hungarian Empire calculated that their best hope was to draw the full weight of the tsar’s armies onto themselves, giving the Germans every opportunity to win the war in the west before the Russians could put enough forces into the field. When these initial plans failed, senior commanders struggled to come up with alternative strategies, trying usually without success to learn from the errors of the opening campaigns. To a very large extent, the one shining victory of the opening phases of the war – the German triumph at Tannenberg in September 1914 – left commanders on all sides attempting in vain to recreate the great encirclement. They repeatedly saw the endless stalemates as anomalies; the reality was that it was Tannenberg that was the anomaly, achieved at a time when there was still open ground between formations, allowing corps and armies to be outflanked – by the time they became aware of German movements, it was too late for the Russians to react. As the war continued, the density of troops prevented any such advantage being achieved.