Blockade of Bulgaria's Aegean coast

At 6 a.m. on 16 October 1915 a naval blockade of the Bulgarian coast of the Aegean Sea came into force. It was declared by Vice-Admiral John de Robeck, commander of the Allied squadron in the eastern Mediterranean, made up mainly of British and French ships. Ships of neutral states were given 48 hours to leave the blockaded area. That same day the British Foreign Secretary, Edward Grey, notified the governments of the neutral states of the blockade. His note to the United States ambassador in London found its way into the American diplomatic documents published later. The French government sent Washington an identical notification two days later.

A response to Bulgaria’s entry into the war

The blockade was the Entente fleet’s first step against the new enemy. On 14 October Bulgaria declared war on Serbia and at once sent its armies against her. According to the British official history, de Robeck, although he had trouble enough at Gallipoli, had for some time been ready to declare a blockade and bombard the Bulgarian ports. When Bulgaria attacked Serbia, he received orders from London to declare a blockade immediately with a two-day period of grace. He was also to check from the air whether there were military targets on the coast worth bombarding. The next day Britain declared war on Bulgaria, and on 16 October France did so. The Admiralty, however, rejected the idea of a landing at the Turkish port of Enos, from which Bulgaria could have been attacked. It was judged that there was no shelter from the winds and no facilities for unloading there, and the fleet was already overstretched.

Bulgaria’s window on the Aegean

Bulgaria had had access to the Aegean only since the Balkan Wars. Its coast stretched from the mouth of the Mesta, beyond which lay Greece, to the area of the mouth of the Maritsa and Turkish Enos. The largest port was Dedeagach (PL), today the Greek Alexandroupoli, and the smaller ones were Porto Lagos, Maronia and Makri. Along the coast, inland, ran the railway from Salonika to Constantinople, which came down to the sea itself at Dedeagach. After the agreement with Turkey concluded in September, the whole line from the interior of the country to this port lay on Bulgarian soil.

The blockade was meant to cut Bulgaria off from seaborne trade, which was already hampered in any case. At the beginning of October the British had announced that they would stop all goods bound for Bulgaria via Dedeagach. The British also suspected that fuel depots were being set up at Porto Lagos, at Dedeagach and in the mouth of the Maritsa for the German submarines which since May had threatened the fleet at the Dardanelles. The blockade of the coast of Asia Minor, declared by the British in June, had a similar purpose.

The Bulgarians expected an attack from the sea. According to reports from Athens, they extinguished the lighthouses on their coast, entry into the port of Dedeagach was allowed only by day and with a pilot, and the ports were said to be mined. British reconnaissance trawlers reported that trenches were being dug and wire entanglements put up along the coast without a break, as though a landing was feared. Five days later Entente ships bombarded the Bulgarian coast for the first time.