Outbreak of the war
End of the war

The Sixtus Letters – Karl’s quest for a way out

Emperor Karl recognized that Austria-Hungary’s continuation of the war in alliance with Germany would mean the end of the Habsburg Monarchy. At the beginning of 1917, in a very round-about way, he initiated investigations into the possibility of concluding a peace with the Entente Powers.

The role of mediator in these investigations was taken by Karl’s brother-in-law, Empress Zita’s brother Sixtus von Bourbon-Parma, with the strictest secrecy being observed in the initial discussions. Between January and March 1917 he cautiously sounded out the conditions of the Entente Powers (most especially France) for a swift conclusion of peace. The correspondence took place in the form of letters composed in French and delivered by Sixtus – hence the name ‘Sixtus Letters’ for the clandestine communications. The whole enterprise was undertaken solely by Karl and his brother-in-law. In spite of the noble aim of bringing peace, one cannot but be surprised at the naivety and amateurishness of their approach to such a complex situation.

It soon became clear what the decisive sticking point would be, namely, the Western Powers’ demand for the cession of Alsace-Lorraine to France and the re-establishment of Belgium as an independent neutral state, which would have hit at the very heart of Germany’s war aims. Although Karl in fact had no influence in these matters, he offered his full support for the Allies’ demands. Foreign Minister Czernin, who was only peripherally involved, considered that the undertaking had little chance of success and emphasized the importance of remaining loyal to the alliance with Germany. In doing so he was expressing views that were directly opposed to Karl’s – a disagreement that was later to have fatal consequences.

After a first attempt to sound out the German alliance partner had proved unsuccessful, a personal visit by Karl to Kaiser Wilhelm proved equally ineffective. Although Karl was frank about the catastrophic state of the Danube Monarchy and absolute necessity of a swift peace, Berlin, encouraged by current successes on the battlefield, held firmly to its demand for a victorious peace and refused to give up Alsace-Lorraine and Belgium.

Moreover, the negotiations being conducted at the same time with the Entente Powers also finally failed on account of Karl’s unwillingness to cede Austrian territory in the Trentino to Italy, which was the condition for Italy’s agreement, as became clear in the course of the talks.

A further reason for the failure of the exploratory talks was that Karl was seeking a comprehensive peace that would also include Germany, while the Entente Powers were only offering a separate peace for the Habsburg Monarchy. For Karl, this would have meant changing sides, which, given the widespread commitment to ‘Nibelung loyalty’, would have had massive political repercussions in Austria; in addition it would also have been a risky undertaking in the military field as German and Austrian units that had hitherto operated in harness would suddenly have become enemies.

So it was that Karl’s peace initiative came to nothing. Although it was not the only one of its kind undertaken by the warring parties, it was regarded as particularly important because of the Emperor’s personal involvement. However, it was not so much its failure that did the Habsburg Monarchy lasting harm but, rather, its bitter postlude: the ‘Sixtus Affair’ was to have fatal consequences for Karl’s position.

Translation: Peter John Nicholson


Griesser-Pečar, Tamara: Die Mission Sixtus, Wien 1988

Kann, Robert A.: Die Sixtusaffäre und die geheimen Friedensverhandlungen Österreich-Ungarns im Ersten Weltkrieg, Wien 1966

Rauchensteiner, Manfried: Der Erste Weltkrieg und das Ende der Habsburgermonarchie 1914–1918, Wien u. a. 2013

Contents related to this chapter


  • Aspect

    Power blocks

    At the start of the war France, Britain and Russia formed the Triple Entente, extending the existing Entente Cordiale between Britain and France. The aim was to curb the ambitions of the German Empire under Wilhelm II to become a major power. Italy joined the war in 1915 on the side of the Entente. On the other side were the Central Powers consisting of the German Empire, Austria-Hungary, Bulgaria and the Ottoman Empire. In 1917 the USA entered the war on the side of the Entente, marking a decisive turning point that was to lead to the military collapse of the Central Powers.

Persons, Objects & Events


  • Development

    Austria-Hungary and Germany: complicated relations

    Vienna and Berlin became closely associated following the Dual Alliance of 1879, although the Habsburg Monarchy was the junior partner. Its dependence in terms of foreign policy became all the more clear after the political unification of Germany in 1871 made it the dominant power in Central Europe. In domestic policy as well, dependence on the Hohenzollern empire made the German element predominant in the multi-ethnic state. The German-speaking populations were split in their identification with Austria and Germany.