It has been proved by the German historian, von Sybel, that the first serious suggestion to Prussia that she should take both the Duchies came secretly from Napoleon III.

It was in vain that Lord John Russell suggested a sensible compromise, namely, the partition of Schleswig between Denmark and Germany according to the language-frontier inside the Duchy.

To this the belligerents demurred on points of detail, the Prussian representative asserting that he would not leave a single German under Danish rule.

The war was therefore resumed, and ended in a complete defeat for the weaker State, which finally surrendered both Duchies to Austria and Prussia (1864)[2].
[1] Lord Wodehouse (afterwards Earl of Kimberley) was at that time sent on a special mission to Copenhagen.

When his official correspondence is published, it will probably throw light on many points.
[2] Sybel, _Die Begruendung des deutschen Reiches_, vol.iii.