From 1914 to 1919, the Allied powers restricted the maritime supply of raw materials and foodstuffs to the Central Powers. The policy is often called a key component in the Allied victory, but it resulted in hundreds of thousands of civilian deaths, and introduced the world to a terrifying new kind of warfare.
The Great War is primarily remembered for its stifling land battles, but one of the conflict's largest and most sophisticated operations was conducted primarily at sea. Right from the start of the war, and until the mid part of 1919, the Allied powers, led by Britain's powerful sea fleet, obstructed Germany's and Austria-Hungary's ability to import goods. The basic idea was to starve the Central Powers and their military into submission.
A Violation of International Law
Despite its best efforts to do so in the preceding decades, Germany was never able to catch up to Britain in terms of its ability to control the seas. Once hostilities commenced in August 1914, Britain began restricting access to the North Sea, instituting checks on the shipping passing through the English Channel and posting a force, the X Cruiser Squadron, to patrol between the Shetland islands and Norway. As a result, German maritime trade was confined to the Baltic.
It was an action that, quite understandably, shocked and outraged the Central Powers. As the global conflict began to take on the character of an attritional war, the encircled combattants became rightfully worried of the stranglehold.
Though largely forgotten by history, the actions of the British were in contravention of international law. According to the 1856 Declaration of Paris (still in force in 1914), blockades were permitted, but only if they were so-called "effective" blockades — meaning that blockades should only take on the form of a cordon of ships off an enemy port or coast. Blockades 'from a distance' were strictly prohibited.
The blockade also violated the 1909 London Declaration which established the rules under which items could be confiscated (Britain was not a signatory, but the international community — especially the United States — still expected Britain to honor the spirit of the Declaration; it was, after all, Britain's idea).
As noted by historian Alexander Watson, the actions of the British "placed [them] outside the pre-war moral consensus on how naval warfare should be conducted."
'Starvation War'
The German government, military, and civilian population reacted to these measures with great fear and anger. The British were denounced for waging a 'starvation war.' German food experts worried that their country was about to become 'hermetically sealed' from the rest of the world and that their enemies were trying to "vanquish our people through hunger." And in an era before the term 'concentration camp' had acquired its notorious association with Nazi genocide, German commentators accused Britain of wanting to turn Germany into a gigantic concentration camp.
Germany had good reason to be worried. On average, nearly 77% of the total import tonnage was raw materials and chemicals needed to fuel the tremendous needs of Germany's industrial power. A large portion of these chemicals were sodium nitrate — a compound used to replenish nutrients lacking in the poor quality soil found throughout the country. Another 17.5% of the imported tonnage was foodstuff, while the remaining 4-5% of German imports were manufactured goods. It's estimated that 45% of all domestically produced foods were connected in some way to foreign imports.
Prior to the war, German Military planners feared such a strangulation scenario. As noted by Alfred von Schlieffen — architect of the famous plan that bore his name — "[long wars] are impossible in an age when the existence of the nation is founded upon the uninterrupted continuation of trade and industry...A strategy of exhaustion cannot be conducted when the maintenance of millions depends upon the expenditure of billions."
These inherent geographical and geopolitical limitations drove the point home that a military victory would have to happen swiftly, preferably within a few weeks or several months. A war lasting for years would represent a complete catastrophe. Which turned out to be the case.
Dwindling Food Stocks
Sadly, while the military planned for a quick war, Germany's politicians did little to prepare for a prolonged conflict in which the availability of foodstuffs would be greatly curtailed. It took months for the government to implement meaningful measures, such as price control and rationing.
Initially, Germany's limited food supplies were made available to the military and rural population. As a result, urban-dwellers experienced almost immediate shortages as prices rose by almost 100% in the first year of the war. Both local and central authorities attempted to fix maximum retail prices for food and clothing, including bread rationing. Such behavior was encouraged after the infamous Schweinenmord — the great pig killing — of 1915 when some 9 million pigs were slaughtered as an effort to divert grain consumption from animals to humans. But the dramatic action meant that, after a brief glut, meat would become even scarcer and more expensive over the coming years. It also deprived German farmers of important fertilizer.
In response to the blockade, Germans were asked to economize. In his book Ring of Steel, Alexander Watson explains:
Bread and flour rationing, entitling each adult to a daily 250-gram portion, was introduced first in Berlin in January 1915 and then extended across the Reich. In the spring, cake baking was forbidden and Tuesdays and Fridays were declared 'meatless days.' As well as bans and controls, there was also innovation of a sort. In October 1914 one of the war's iconic foodstuffs, K-Brot, was launched on the German public. It was never openly stated whether the 'K' stood for 'Krieg' (war) or "kartoffel' (potato), but this bread, in its first incarnation at the end of October 1914 was rye or 'grey' (rye and wheat) bread with 5 per cent potato four. The proportion of potato was soon raised to 10 percent due to the growing scarcity of grains and, in January 1915, so-called KK-Brot containing 20% potato flour was introduced. The attack on an item so fundamental to German life as bread was a daily reminder to Germans that, as sixteen-year old Hilde Gotting wrote in her diary in February 1915, 'England's greatest and most fervent wish is to starve us out!
The urban poor had to resort to bread queues when foodstuffs were not available, and food riots often broke out if they were not.
After the winter of 1916-17, the potato crop failed and Germany was reduced to a diet largely based on turnips. The result was a prolonged period of hunger and misery. In his book War of Attrition, historian William Philpott quotes Toni Sender, a German woman who recalled the shortages:
The worst winter, that of 1917, when almost all food consisted in whole or in part of turnips...Bread made of flour mixed with turnips, turnips at luncheon and dinner, marmalade made of turnips — the air was filled with the smell of turnips and it almost made you vomit! We hated turnips and had to eat them. They were the only food stuff obtainable in abundance.
I soon realized that a great change in the mentality of the people was taking place. They had lost their confidence in Hindenburg and Ludendorff, in the whole General Staff.
Indeed, the war wouldn't last much longer, expiring by November the following year.
Meanwhile in England, propaganda claimed Germans were subsisting on glue soup. The effort was meant to show how desperate the Germans were becoming.
The Aftermath
But the damage was done. Estimates vary on the number of Germans killed as a result of the Allied blockade, but they're horrific nonetheless. As early as 1918, the German Board of Public Health claimed that 763,000 German civilians died —either directly or indirectly— from malnutrition, starvation, and disease caused by the blockade up until December 1918. Ten years later, a separate German study sponsored by the Carnegie Endowment for International Peace placed the death toll at 424,0000.
Historian David. A. Janicki offers this analysis:
The situation in Germany going into 1917 was one of growing chaos, disorganization, and sickness all stemming from the blockade, and subsequently Germany's inability to provide its people with adequate provisions to sustain normal productive lives. While few individuals starved to death between 1914-1918 - official British post-war statistics counted that 772,736 starved to death because the blockade - millions did succumb to malnutrition which led to severe decreases in body mass, and nearly constant suffering from various medical ailments. According to a post-war analysis conducted by University of London physiologist Ernest Starling, throughout 1917-1918, the average German ate less than 1500 calories per day, down from the already meager diet of 1700 calories per day in 1916. Both of these averages were of course significantly less than the 4020 calories per day consumed by the average German in the pre-war years. Starling contends that these drops in the provisions caused the average civilian's body weight to drop by as much as 15-20% by the end of 1917.
These unsustainable eating habits, and unhealthy weight loss caused a greater proportion of the German population to suffer from a host of chronic illnesses which ranged from mild ailments like influenza and dysentery, to more serious afflictions such as typhus, tuberculosis, and scurvy. Vincent noted that between 1917-1918, the number of tuberculosis related deaths increased seventy two percent when compared to 1913 statistics. One possible reasoning for this drastic increase in fatalities is that without access to foods containing proper nutrients, the body's immune system begins to shut down, leaving the individual highly susceptible to contracting communicable diseases.
It's impossible to know how many Germans died from the Spanish Influenza epidemic as a result of malnutrition, but some estimates place it as high as 200,000.
Looking back on this dark episode a century later, it's tempting to say that the Allies were acting in accordance with the demands of a 'total war.' Indeed, a hallmark of 20th century warfare is the abject willingness of all combatants to set aside convention and legal constraint. The Germans were guilty of their own atrocities as well during the war, including the use of gas on the battlefield and the killing of civilians when troops swept through Belgium in 1914. As the conflict made abundantly clear, wars would never be fought in the old ways ever again.
What's more, the blockade (arguably) influenced similar events later in the 20th century. During 1932-1933, Joseph Stalin deliberately starved anywhere from 4 million to 7.5 million Ukrainians in the Holodomor. Adolf Hitler's Hunger Plan, which (mercifully) never got off the ground, was intended to kill tens of millions of Slavs and Jews in the 'bloodlands' to the east of Germany. And lastly, the Nazis themselves tried to 'starve' the British into submission by implementing their own blockade during the Second World War.
Sources: Ring of Steel by Alexander Watson | The First World War by Hew Strachan | A World Undone by G. J. Meyer | "The British Blockade During WWI" by David A. Janicki | The First World War By Ian J. Cawood et al