Since the early 18th century, trade blockades had been a vital coercive element in the maintenance of British naval supremacy. This supremacy was still very much intact when war broke out in August 1914. The British government moved immediately to strangle the supply of raw materials and foodstuffs to Germany and its allies. This marked the beginning of the 'hunger blockade', a war of attrition that lasted until Germany signed the Treaty of Versailles in June 1919.

Armed with contraband lists, British naval ships spent the war patrolling the North Sea, intercepting and detaining thousands of merchant ships thought to be harbouring cargo bound for enemy shores. This aggressive display of maritime power aroused considerable anger in neutral countries, many of whom enjoyed strong trading links with Germany.

Tension was heightened after the North Sea was declared a British 'military area' on 3 November 1914. Despite complaints about breaches of international law, however, most neutral merchant ships agreed to put into British ports for inspection and were subsequently escorted - minus any 'illegal' cargo bound for Germany - through the British-laid minefields to their final destinations.

The blockade strategy worked effectively. As a memorandum to the War Cabinet on 1 January 1917 stated, very few supplies were reaching Germany or its allies - either through the North Sea or through other areas such as Austria's Adriatic ports, subject to a French blockade since the first month of the war.

Germany attempted to counter the crippling effects of the blockade with a new weapon that seemed capable of subverting British naval superiority: the submarine. For much of the war, German submarines (or 'U-boats') were deployed only intermittently against neutral and Allied shipping. Their devastating impact - as witnessed, for example, in the sinking of the Lusitania in May 1915 - was offset by the international opprobrium that such attacks aroused.

From 1 February 1917, however, the German naval command adopted a policy of 'unrestricted submarine warfare'. Despite initial successes, this high-risk strategy did not work. It finally provoked the USA into entering the war against the Central Powers (in April 1917) and its worst effects were successfully countered by the introduction of a convoy system. The blockade continued unabated.

Such schemes, however, enjoyed only limited success. The average daily diet of 1,000 calories was insufficient even for small children. Disorders related to malnutrition - scurvy, tuberculosis and dysentery - were common by 1917.

Official statistics attributed nearly 763,000 wartime deaths in Germany to starvation caused by the Allied blockade. This figure excluded the further 150,000 German victims of the 1918 influenza pandemic, which inevitably caused disproportionate suffering among those already weakened by malnutrition and related diseases.

Although the blockade made an important contribution to the Allied victory, many of its devastating side effects cast a long shadow over post-war German society.