Grey gives assurances to Supilo

On 30 August 1915 the British Foreign Secretary, Edward Grey, received in London the Croatian politician Frano Supilo, vice-president of the Yugoslav Committee. According to a British chronology of the war, Grey told him that if Serbia agreed, the Allies could guarantee ultimate freedom and the right of self-determination to Bosnia, Herzegovina, southern Dalmatia, Slavonia and Croatia. The date of the conversation is confirmed by the dispatches of the Serbian minister in London, Mateja Bošković, studied by the historian Dragan Bakić. In a later Foreign Office memorandum of 1916 the same statement is dated 1 September, perhaps because that was when it was handed over in writing.

The Croat from Cavtat

Supilo came from Cavtat near Dubrovnik. Before the war he was one of the leaders of the Croat-Serb Coalition, which governed Croatia-Slavonia. After the assassination in Sarajevo he fled to Italy, and together with Ante Trumbić and the sculptor Ivan Meštrović he created the Yugoslav Committee, which from May 1915 operated in London. The émigrés from Austria-Hungary wanted all Serbs, Croats and Slovenes united in a common state. Supilo favoured a federation of equal lands and distrusted the Serbian Prime Minister, Nikola Pašić, whom he suspected of aiming at a Greater Serbia. The Russian Foreign Minister, Sergei Sazonov, told him bluntly that Russia supported a Greater Serbia, not a Yugoslav state.

The summer brought Supilo nothing but bad news. In the spring, in the secret Treaty of London, the powers had promised Italy Istria and a large part of Dalmatia, inhabited by Croats. On 15 August the Entente, courting Bulgaria, presented Serbia with a list of gains in return for concessions in Macedonia: Bosnia and Herzegovina, Syrmia, Bačka and part of the Dalmatian coast, and perhaps Slavonia as well. The fate of Croatia proper, with Rijeka, was to be decided by the peace treaty. Supilo feared that his country would be divided between Italy, Serbia and Hungary. He did not want the South Slav lands of the Habsburg monarchy to be handed out as compensation to Serbia without asking their inhabitants.

Self-determination instead of compensation

Supilo therefore lobbied in London for the future of these lands to be decided by their people. Grey was not opposed to the idea. As early as 16 August he had instructed his minister in Niš to reassure the embittered Pašić that the question of Croatia remained open. The assurance given to Supilo went further. It did not promise these lands to Serbia, but the right of choice to those concerned. It made this conditional, however, on Serbia’s consent, and so in practice on its acceptance of the Allies’ demands regarding Macedonia. It was also only an oral statement by the minister, not an undertaking by all the powers. Italy, which objected even to the mention of Slavonia in the note to Serbia, had no part in it.

For Supilo it was a success. In the Foreign Office’s later assessment, Grey’s statement was far closer to Yugoslav ideals than the earlier promise to Serbia, which had assured it Bosnia and Herzegovina and broad access to the Adriatic after the war. The Serbian legation received it with unease. Bošković, to whom Supilo described the conversation, drew Pašić’s attention to Grey’s interest in Croatia and Slavonia. He suspected that behind it lay the idea of an independent Croatia, and advised that Serbia should demand Slavonia unconditionally, without any vote.

What came next

On 1 September Serbia replied to the Allies. It agreed to concessions in Macedonia, but demanded, among other things, the annexation of Croatia and the western Banat and the right of the Slovenes to decide on union with Serbia. A few weeks later Bulgaria entered the war on the side of the Central Powers, and Serbia was defeated and occupied, so the negotiations lost their meaning. The dispute between Supilo and Pašić over the shape of the future state went on. In June 1916 Supilo left the Yugoslav Committee. He died in London on 25 September 1917.