Britain declares war on Bulgaria

On Friday 15 October 1915 Great Britain found itself at war with Bulgaria. A short Foreign Office statement, published the next day in a supplement to the official London Gazette, read: “Owing to the King of the Bulgarians, an ally of the Central Powers, being now at war with the King of Serbia, an ally of His Majesty King George V, His Majesty’s Government have informed the Swedish Minister in London, who has charge of Bulgarian interests in this country, that a state of war exists between Great Britain and Bulgaria as from 10 p.m. today.”

Two days earlier London had broken off diplomatic relations with Sofia, and on 14 October Bulgaria and Serbia declared war on each other. According to the British official history of naval operations, London had for several days been pressing its allies to turn Russia’s breaking of relations into war at once. The British got ahead of both France and Russia in this. The British official history of the Macedonian campaign gives the date as 14 October, but the Foreign Office statement is dated 15 October, and that is the date given by contemporary chronicles.

“A state of war”

The statement was not a declaration of war in the classic form. The British government sent no note to Sofia, because it no longer had a minister there. Nor did it list any Bulgarian wrongs against Britain, because there were none. It merely stated that, since Bulgaria was fighting an ally of Britain, a state of war existed between the two countries, and informed the neutral state that looked after Bulgarian affairs in London. The same had been done a year earlier with Turkey. Then the Foreign Secretary, Edward Grey, had notified the United States ambassador in London of the state of war, and France had proclaimed it on the same day.

The formula describing Serbia as an ally had its significance. Before the war Britain had not been bound to Serbia by any treaty. Grey had recalled this the day before in the House of Commons, but added that from the beginning of the war the British, together with their allies, had given Serbia all the help their position allowed. Serbia, he said, was fighting for her existence, but the struggle was one, on whatever front it was fought.

The royal proclamation

On 16 October King George V signed at Buckingham Palace a proclamation extending to the war with Bulgaria all the proclamations and orders issued earlier in connection with the war with Germany, Austria-Hungary and Turkey. Bulgaria became an “enemy country” and its subjects “persons of enemy nationality”. Loans to the Bulgarian government and any dealings with it were forbidden. One exception arose from maritime law. Bulgaria had not ratified the Hague Convention of 1907 on the status of enemy merchant ships at the outbreak of hostilities, so Bulgarian ships were not given the period of grace that in August 1914 Britain had allowed enemy ships to leave its ports.

In the Balkans the war with Bulgaria changed little for the time being. At Salonika the first British and French divisions were only just disembarking. According to the British official history of the Macedonian campaign, General Bryan Mahon, commanding the British 10th Division, had orders not to move despite the declaration of war, and London had not yet decided whether further reinforcements should go to Salonika at all. At sea the war came faster. Vice-Admiral John de Robeck was ordered to declare a blockade of the Bulgarian Aegean coast and to reconnoitre targets for bombardment from the air.