The prolonged naval blockade was conducted by the Allies during and after World War I[1] in an effort to restrict the maritime supply of goods to the Central Powers, which included Germany, Austria-Hungary, and the Ottoman Empire.

[7] However, it has been pointed out that there was an even slightly larger civilian excess mortality during the war in the United Kingdom, a country that was much less affected by food shortages (although this can also be attributed to the influenza epidemic and diseases such as bronchitis and tuberculosis which were not strictly nutrition-related).

Imports of foodstuffs and war materiel to the European belligerents came primarily from the Americas and had to be shipped across the Atlantic Ocean, which made Britain and Germany aim to blockade each other.

Germany was initially able to use neutral countries as a conduit for global trade, but eventually British pressure, American involvement, and German missteps led to full economic isolation.

A key component of German military thinking was the realization that notwithstanding food supplies, Germany's prospect of winning a long war with relatively weak allies against the United Kingdom, France and Russia was dubious in any case.

However, once it became clear that the Schlieffen Plan had failed and that Germany would have to fight a long war on two fronts, factors such as the conscription of farm laborers, the requisition of horses, poor weather and the diversion of nitrogen from fertilizer manufacture into military explosives all combined to cause a considerable drop in agricultural output.

[19] In March 1916, at the suggestion of Robert Peet Skinner, the United States Consul General in London, the inspection procedure was considerably simplified for neutral shipping.

A certified manifest could be sent in advance by telegram to the local British embassy, which, if agreed, could issue a document known as a "navicert", which was forwarded to the Admiralty and would allow the cargo to pass through the blockade without the need for inspection.

[20] The British Isles formed what Admiral Beatty described as "a great breakwater across German waters thereby limiting the passage of vessels to the outer seas to two exits".

[22] A memorandum to the British War Cabinet on 1 January 1917 stated that very few supplies were reaching Germany or its allies via the North Sea or other areas such as Austria-Hungary's Adriatic ports, which had been subject to a French blockade since 1914.

Neutral shipping was tempted by high prices to smuggle strategic materials such as rubber, cotton or metals, which could be hidden from inspection or listed as personal luggage.

Things only worsened with the February 1917 German declaration of unrestricted submarine warfare (which meant a loss of neutral tonnage, both through ships sunk and Allied requisition of vessels) and the subsequent American entry into World War I (which added immense US pressure to British efforts).

But the Hjalmar Hammarskjöld government fell the next year, and combined Anglo-American pressure forced increasing restrictions on export to Germany until a full prohibition in May 1918.

Although at the outbreak of war, stocks of strategic materials amounted to only three to six months of pre-war consumption, Germany was able to mitigate the effects of the blockade in a number of ways.

[30] Other shortages were mitigated by substitution, aided by Germany's well-developed chemical industry and university research departments; an example is the extraction of saltpeter from ammonia made by the Haber–Bosch process.

[33] The official German account, based on data about disease, growth of children, and mortality, harshly criticised the Allies by calling the blockade a crime against innocent people.

[34] The first account commissioned by the Allies was written by Professor A. C. Bell and Brigadier-General Sir James E. Edmonds, hypothesised that the blockade led to revolutionary movements but concluded that based on the evidence, "it is more than doubtful whether this is the proper explanation".

[35] Edmonds, on the other hand was supported by Colonel Irwin L. Hunt, who was in charge of civil affairs in the American occupied zone of the Rhineland, and held that food shortages were a post-armistice phenomenon caused solely by the disruptions of the German Revolution of 1918–19.

[38] The food shortages were so severe that by the autumn of 1918, Austria-Hungary hijacked barges on the Danube full of Romanian wheat bound for Germany, which in turn threatened military retaliation.

[40] A complicated rationing system, initially introduced in January 1915, aimed to ensure that a minimum nutritional need was met, with "war kitchens" providing cheap mass meals to impoverished civilians in larger cities.

For example, the Hindenburg Programme of economic was launched on 31 August 1916 and designed to raise war productivity by the compulsory employment of all men between the ages of 17 and 60, meeting only partial success.

The military was the true priority, with the 10% of the population in the armed forces allotted 30% of grain and 60% of meat supplies, in addition to foodstuffs looted from the occupied territories.

Even as a food crisis loomed on the eve of the armistice, the army built up a reserve of 1.5 million tons of grain (equivalent to 7 months of pre-war imports), plus other foodstuffs, for a possible last-ditch battle.

[6] The Americans were most concerned about the bad conditions in Germany, with US Food Administrator Herbert Hoover desiring an almost immediate end to the blockade so the US could sell its surplus.

[49] For the Germans, in negotiations from January 1919 to March 1919, they refused to agree to the Allied demand to temporarily surrender its merchant ships to their control so as to provide transport.

[51] Privately, German authorities had initially considered the armistice only a temporary cessation of the war (so that they can regroup their forces), and feared that when fighting broke out again, the ships would be confiscated outright.

[59] The British Labour Party antiwar activist Robert Smillie issued a statement in June 1919 condemning continuation of the blockade and giving the same figure.

[60][7] From a more modern perspective, in 1985 C. Paul Vincent found that no reliable death toll data exist for the period immediately after the November 1918 armistice, but maintains that for the German people, they were the most devastating months, as "Germany's deplorable state further deteriorated.

"[61] N. P. Howard places half of his overall estimate of 474,085 excess civilian deaths (including influenza) into the postwar period, but attributes around 100,000 to incipient famine conditions in the first month.

Conditions greatly improved after soldier's councils raided large military food reserves (set aside for a continuation of the war) and gave them to the civilian population.