Perhaps 'missing believed dead' is a little strong but some sources allege that Talleyrand suggested to Metternich that, if the Emperor failed to return from Spain, a successor the Austrians might find more favourable to them could be found. In other words he offered to try and alter the line of succession if the Emperor did not return. He supposedly showed letters from Fouche and Champagny to support his argument (See Dard, Emile, Napoleon and Talleyrand, London, Philip Allan & Co Ltd, 1937 - translated by Christopher Turner, p199). Historians speculate that Talleyrand was actively trying to distance himself from Napoleon after 1807 and the Emperor dismissed him from the post of Grand Chamberlain of the Empire for this and various other intrigues on his return from Spain.

Regards,

David