Naval blockade

A naval blockade is the cutting off of an enemy’s coasts from seaborne trade by a navy. In the First World War the word means above all the blockade of Germany, which Britain began in August 1914 and whose last restrictions were lifted only in July 1919. It did not close German ports with warships stationed off their entrances, but cut them off from a distance.

A distant blockade

A classic blockade required warships to watch the blockaded coast at all times. That is how the Allies blockaded Cameroon in 1915 and Greece in December 1916. Off the German coast, however, blockading ships would have been easy targets for mines, torpedo boats and submarines. So the British closed the exits from the North Sea instead: patrols in the English Channel and between Shetland and Norway stopped ships for inspection.

In the north this duty fell to the 10th Cruiser Squadron, at first with old warships such as Hawke, sunk in October 1914, and later with auxiliary cruisers.

Ships were stopped because of contraband, whose lists London announced on 4 August 1914. The law of naval warfare was meant to be set out by the Declaration of London of 1909. Britain had not ratified it, but agreed to apply it with its own changes. The most important was the doctrine of continuous voyage: a cargo bound for the neutral Netherlands or Denmark could be seized if it was in fact destined for Germany. Successive orders widened these powers until, in July 1916, the Allies abandoned the Declaration.

On 2 November 1914 the Admiralty declared the whole North Sea a military area and directed neutral shipping onto set routes, where it was easier to search. When Germany declared the waters around the British Isles a war zone, the retaliatory Order in Council of 11 March 1915 allowed the seizure of all goods going to or coming from Germany. Edward Grey now called the new measures a blockade outright.

The neutrals

The hardest task was telling neutral trade from trade with the enemy. In the Netherlands the Netherlands Overseas Trust guaranteed to the British that imported goods would not be resold to Germany, and in other countries similar agreements were made with merchants’ associations. Firms trading with the enemy were put on the black list. From February 1916 the whole effort was directed by Lord Robert Cecil, the Minister of Blockade. Compulsory rationing was introduced at the same time: cargoes were held back once a neutral country’s imports of a given commodity exceeded their pre-war level.

The neutrals, above all the United States, protested, but once in the war the Americans tightened the blockade further, and in 1918 the Allies ran it through a joint committee in London.

Hunger and the German answer

Before the war Germany imported about a third of its food. On 22 February 1915 Berliners received bread cards, and after the potato harvest failed came the turnip winter of 1916–1917, when rations fell to about a thousand calories a day. The blockade was not the only cause of hunger: the countryside lacked labourers, horses and fertiliser. How many people it killed is not known exactly. Wartime German statistics gave 763,000 civilian deaths from malnutrition and disease, a 1928 study 424,000.

Germany presented submarine warfare as its answer to the blockade. Its battle fleet could not break it, and after the Battle of Jutland the Royal Navy still ruled the sea. What remained were the submarines, with which Germany hoped to cut Britain off from its own supplies from overseas.

The Armistice of Compiègne left the blockade in force, although the Allies promised to see to Germany’s essential supplies. American food began arriving in March 1919, and the last restrictions were lifted on 12 July 1919, after the signing of the Treaty of Versailles.