Peace treaties were concluded with the defeated powers in 1919 and 1920: Versailles with Germany; St Germain with Austria, Neuilly-sur-Seine with Bulgaria; Trianon with Hungary and Sèvres with the Ottoman empire. From these treaties emerged the new states of Poland, Czechoslovakia, and Yugoslavia; Lithuania, Latvia, and Estonia appeared from other agreements. Serbia and Montenegro were merged into the new Yugoslavia, Romania was greatly enlarged, and Bulgaria shorn of most but not all of its acquisitions since 1912. A number of territorial issues could not be settled immediately; in some cases resort was made to plebiscites, in others international or ambassadorial conferences settled the day, as when the disputed Italo-Yugoslav border was delimited at Rapallo in 1920, or when the ambassadors of the great powers pronounced their judgement of Solomon on Teschen, an area disputed between Poland and Czechoslovakia. In some regions, particularly after the mass armies had been demobilised, the allies had no leverage and the final solution was left to the arbitration of arms.
The post-war settlement was based supposedly on the principle of national self-determination. Because it was believed the nationalism of the subject peoples had been such a disruptive force in the past, nation states were considered the best future guarantors of the status quo. Yet there were many compromises. Czechoslovakia was by no stretch of anyone’s imagination a nation state; it emerged because the Czechs persuaded the victorious allies that they were the best safeguard against German, Hungarian, and Austrian revanchism and against German, Hungarian, and Russian bolshevism. For strategic reasons the Czechs were given control over Ruthenia, just as the Yugoslavs took the Hungarian-dominated Bačka which they believed essential to the defence of Belgrade. The Versailles settlement was unable, and did not attempt, to allow every European to live in his or her own national state, but the post-war treaties ‘still freed three times as many people from nationally alien rule as they subjected to it’. 1 Furthermore, the victors knew that the pure nation state could not be created in an area where there were so few clear-cut divisions between different ethnic groups. It was a mark of the civilisation of the men of Versailles that, realising this, they strove to provide protection for the minority groups which would inevitably be