Primary Documents - German Declaration of Naval Blockade of Britain, 4 February 1915

Kaiser Wilhelm II Reproduced below is the official German declaration of a naval blockade of Britain dated 4 February 1915.  Issued by the Chief of Marine Staff Hugo von Pohl - and in the face of opposition by Alfred von Tirpitz (who believed it to be premature) - the declaration, supported by Chancellor Theobald von Bethmann-Hollweg, warned neutral countries that shipping around the U.K. was at risk of being sunk without warning by German U-boats.

The United States, which sent much commercial shipping to Britain, immediately protested, as a consequence of which the German declaration was withdrawn by Kaiser Wilhelm II.  It was subsequently restated in 1917 and led to U.S. entry into the war.

German Declaration of Naval Blockade Against Shipping to Britain, 4 February 1915

The waters round Great Britain and Ireland, including the English Channel, are hereby proclaimed a war region.

On and after February 18th every enemy merchant vessel found in this region will be destroyed, without its always being possible to warn the crews or passengers of the dangers threatening.

Neutral ships will also incur danger in the war region, where, in view of the misuse of neutral flags ordered by the British Government, and incidents inevitable in sea warfare, attacks intended for hostile ships may affect neutral ships also.

The sea passage to the north of the Shetland Islands, and the eastern region of the North Sea in a zone of at least 30 miles along the Netherlands coast, are not menaced by any danger.

(Signed) Berlin, February 4th,
Chief of Marine Staff.

Source: Source Records of the Great War, Vol. III, ed. Charles F. Horne, National Alumni 1923

'White Star' was a German mixture of chlorine and phosgene gas, so-named on account of the identification marking painted on the delivery shell casing.

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Primary Docs