Winston Churchill had more experience of conflict than most British politicians. By the time he arrived as a Member of Parliament, still in his mid-twenties, he had already been involved in fighting on the Indian Empire’s North-West Frontier, taken part in the British army’s last great cavalry charge at Omdurman in the Sudan, and enjoyed a series of almost Boys’ Own-esque adventures in the Boer War, as well as managing to closely observe the fighting in a Cuban revolt against Spanish rule in the mid-1890s. He seemed at times to relish it. Writing some time later, in a wry style and not entirely seriously, of his first time under fire he noted that:

A lot of people were killed and on our side their widows have had to be pensioned by the Imperial Government, and others badly wounded and hopped around for the rest of their lives, and it was all very exciting and, for those who did not get killed or hurt, very jolly.

The two total wars that shaped Churchill’s later career were a very different matter. As he was to lament in My Early Life, a memoir written in the wake of the Great War, modern warfare had become a ‘mere disgusting matter of Men, Money and Machinery’.

Churchill could at least claim to have seen this coming. In a parliamentary debate held in 1901 he had argued that:

A European war cannot be anything but a cruel, heart-rending struggle which, if we are ever to enjoy the bitter fruits of victory, must demand, perhaps for several years, the whole manhood of the nation, the entire suspension of peaceful industries, and the concentration to one end of every vital energy in the community.

That was to prove a remarkably prescient description of the war that would engulf Europe between 1914 and 1918. The total wars of the 20th century were unlike anything that had come before them. The nature of warfare was transformed and, in both cases, victory was decided not just by events on the battlefield but by the side able to best marshal its resources, manage its production and keep its civilian population – as well as its military – well supplied. In both cases victory was won by the liberal, capitalist democracies.

Most European statesmen or strategists thought the war that broke out in August 1914 would not last long. The Great Power conflicts that had broken out in Europe during the latter part of the 19th century had been relatively brief affairs. The Franco-Austrian War of 1859 lasted around ten weeks, Prussia had defeated Austria in just six weeks in 1866, and the Franco-Prussian War of 1870-71 took just over six months. Further east, the Russo-Turkish war of 1877 – a war closely studied by European militaries – lasted less than a year, and even the relatively long Russo-Japanese War, fought a decade before the Great War, reached its conclusion in around 19 months.

The problem facing the generals in 1914 was that rapid changes in military technology had elevated the power of defensive infantry in a manner few had foreseen. The British Army Staff College course of the 1890s, attended by many colonels who would later serve as generals between 1914 and 1918, was a reasonably up to date affair. The students were well-versed in how the development of breach-loading rifles had increased the firepower of the infantry and how rifled artillery and high explosive shells had increased the potency of the artillery. They studied the lessons of the Russo-Turkish War, alongside those of the Franco-Prussian War, and the American Civil War.

But the most recent developments, such as magazine-loading rifles and machine guns (which increased infantry firepower by an even greater volume), and lyddite shells, which increased the potency of artillery, were not considered in anything like a systematic way.

By Christmas 1914 the war was not over; on the crucial Western Front, it had settled into a pattern that would become dreadfully familiar over the following year, with trench lines stretching from the Channel coast to the Swiss border.

The generals of the Great War were not the donkeys of popular legend, fruitlessly retrying the same old methods of attack – at a great cost in lives – and hoping that somehow, this time, things would turn out differently. There was a great deal of learning and adaption. Infantry tactics changed almost beyond recognition between 1914 and 1918, the handling of artillery became ever more skilful, and both tanks and aircraft became part of the armoury of war. But the First World War and its course cannot be understood by looking at the battlefield alone.

Such attritional battles required not just a constant stream of men to replace casualties, but previously unimaginable levels of munitions. Take, as an example, artillery shells. Close observers of the Franco-Prussian War of 1870-71 had noted the powerful role played by artillery and the crucial edge that modern guns had given Prussia, which, together with its German allies, had fired around 80,000 shells each month. In 1914 the German army was firing closer to 900,000 shells in the same period. By 1918 it was firing almost eight million.

No army or supply organisation had expected anything on this scale. The French army went into the war with a stockpile of five million shells and plans to produce around 100,000 a month. Their stockpile was almost exhausted by Christmas 1914.

The challenge faced by all the powers engaged in 1914 was, as Churchill put in, one of men, machines and money. The war was hungry for all three. Britain had initially sent an expeditionary force of six divisions to France, but by 1918 it had 70 divisions in the field. Over the course of the war, Germany was forced to mobilise almost 14 million men. German units suffered, on average, a roughly three per cent casualty rate every month between 1914 and 1918 – around one third of their strength had to be replaced every year just to stand still.

The question facing policymakers was how to keep up with this demand for men and munitions and how to achieve it without undermining other factors vital to victory. The whole issue was fraught with tough trade-offs. The competing powers needed to keep men fighting in the field, but also needed an adequate pool of workers to keep producing ever-growing volumes of munitions. They needed to devote enough resources to direct war fighting without causing the kind of shortages in the civilian economy that would eventually lead to economic collapse, even revolution. If economics is fundamentally the study of resource allocation, then total war is, at heart, a question of economics.

Unsurprisingly, the demands of total war saw a huge growth in the economic role and power of the state. By 1917 the British government, which before the conflict had had an exceptionally small economic footprint, had extended its borders considerably. Not only was conscription introduced, but the railways, shipping and mines found themselves under state control. By the end of the war, 85 per cent of food was being purchased by the ministry responsible, while the output of whole industries, such as chemicals, was requisitioned by the government. The Ministry of Munitions was directing vast swathes of national output. This new ministry, a wartime innovation, was, by the war’s end, employing two and half million workers and was probably the largest purchasing business and industrial employer in the world.

Measured as a somewhat anachronistic share of national income or GDP, government spending – driven almost entirely by military requirements – leapt to previously unthinkable levels. In both France and Germany, government spending had represented around 10 per cent of national income in 1913; by 1916 it was closer to 50 per cent. Almost half of all national output was now devoted to fighting.

Different states coped with the challenge of total warfare in different ways. All things considered, Britain and her French ally rose to the challenge well. The war was enormously expensive – in both human and economic terms – but the trade-offs were just about managed. British and French generals would frequently complain that they did not have all the men or shells they required for their planned operations, but the front was maintained for four years and, despite some civilian hardship, their domestic economies continued to function.

At the other extreme was the economic weak link of the Entente powers: Russia. Here, total warfare meant economic collapse and, ultimately, domestic revolution.

In Russia, still in 1914 a fundamentally peasant, rural economy, the mobilisation of men and (equally crucially) horses for the front led to a major disruption in agricultural production. Still, given that prewar Russia had exported around 10 per cent of its grain (primarily to powers it was now at war with) the Tsarist regime hoped domestic food supplies would prove adequate. The army mobilised the country’s limited rail network, meaning that moving grain to the cities became trickier. But a larger problem was that there was simply not enough food to move around in the first place.

Before the war, the Russian countryside, like that of other agrarian states across Europe, had generally produced an agricultural surplus; that is to say, it produced more foodstuffs than required for its own consumption. That surplus had been sold on and the cash used to buy manufactured goods produced by urban workers.

But under the pressures of total war, the economic exchange between the cities and the countryside broke down. With Russia’s industries increasingly focused on military production and military needs, there was a change in the terms of trade between cities and the countryside. There were few manufactured goods for civilians available, and those that were tended to be taken by the consumers closest to where they were actually produced, the cities. Even if peasants had continued to produce a surplus as before, they would have little to spend the earnings on.

So, in many cases, they simply stopped. The usual exchange between the rural and urban sectors broke down and the food supply in the cities began to run scarce. The result was the collapse of the governing regime and Russia’s eventual exit from the war.

The German handling of the war and its trade-offs sat somewhere between these extremes. Initially, its War Laws of August 1914 allowed the state to take greater control of transport and of some key raw materials, as well as establishing maximum prices for some activities. By the Autumn of the first year of the war, when it was clear that the early attempt to land a knockout military blow had failed and the war would drag on for longer than hoped, additional steps were needed. The financial incentives available to private firms for undertaking military work were increased, drawing more resources into the war effort. The whole programme changed gear radically in 1916 with the Hindenburg Programme.

Field Marshall Paul von Hindenburg, and his close associate, General Erich Ludendorff, had had a good war up to mid-1916. Commanding German forces on the Eastern Front, they had made substantial gains against the Russian army and, in August of that year, Hindenburg was promoted to chief of the general staff, taking over the running of Germany’s war effort.

In September he, accompanied by Ludendorff, held a conference at Cambrai, near the frontline in occupied northern France, with the commanders of the armies on the Western Front. The problem, according to the field commanders, was that the forces of the Entente had achieved a superiority in artillery.

Faced with the need to increase shell production, Germany’s War Ministry assumed sweeping powers across the wider economy. Employment in the defence industries rose as workers were redirected, while that in the non-defence industries fell dramatically.

On one level, the powers assumed by the German military high command do not look that different to the kinds of economic planning and direction assumed by their opponents in London and Paris, but there were three crucial differences. First, Germany suffered an increasingly damaging hit from a British-led naval blockade, which cut off key imports. Second, unlike Britain and France, Germany suffered from a breakdown in traditional exchanges between the countryside and cities, one that was even more damaging than the breakdown experienced in Russia. Third, and perhaps most important, Germany’s war economy came almost totally under military control.

Whereas the British and French governments assumed sweeping new powers, they remained – just about – within the confines of a civilian-led, democratic state. In Germany, military needs came first and foremost, with civilian requirements a distant second.

Rather than helping to ensure that the military had the resources it needed, by 1918 the dominance of the military contributed to a collapse in the German home front at much the same time that the army in the West was in retreat.

The challenge of a total war, as was to be realised again between 1939 and 1945, was not simply one of maximising munitions production while supplying the military with enough fresh recruits, though that was challenging enough. Britain, after a surge in volunteers in 1914, was already by 1915 having to take some men out of uniform and send them back to the factories and mines.

The real trade-off was how to ensure that the armies at the front had the men and munitions they needed while also keeping the civilian economy afloat and avoiding the kinds of extreme deprivation that would undermine support for both the war effort and, potentially, the political regime itself. In both total wars, liberal, capitalist economies showed themselves to be extremely adaptable to its demands and capable of ramping up production of necessary munitions and supplies. In both conflicts, democratic, civilian-led governments showed themselves to be far better placed to handle the trade-offs between military needs and domestic stability.