On March 27 1815, Lord Castlereagh, in London, writes to the Duke of Wellington, in Vienna. Castlereagh has just learned that Louis XVIII left in Paris the secret treaty between Britain, Austria and France, which was directed against Russia, and other secret documents. Talleyrand’s correspondence and other secret documents were also left behind. The concern was that Napoleon will use these documents to divide the allies. In fact, Napoleon will try to do so but Alexander I, though angry on learning of the Secret treaty, will not break the alliance.
My dear Lord—It is to be presumed, in the hurry of their departure, the Foreign Office at Paris has not been stripped by the King’s Ministers of any of its contents, and consequently that our Secret Treaty with France and Austria, as well as all Prince Talleyrand’s correspondence, will fall into Buonaparte’s hands. He will of course try to turn this to account, first in privately sowing discord; and, if he fails in this, he will expose the whole in the Moniteur. I have desired Sir C. Stuart to ascertain from Blacas how the fact stands, and leave it to your judgment to take such steps as you deem most suitable for counteracting any unfavourable impression.
I flatter myself, after all he knew long since, it cannot produce any unfavourable impression upon the Emperor of Russia’s mind. He must feel assured that the whole grew out of differences now settled, and a most indiscreet declaration of Prince Hardenberg’s. The treaty is, upon the face of it, purely defensive; and all our proceedings since have proved this beyond a doubt.
In haste, ever yours, CASTLEREAGH.