The confederation had determined the matter shortly before the Franco-Prussian war.
The kingdom that was, an admixture of old France and newer Austria, was a gateway which opened the road to the Orient, and a gateman must be placed there who would be obedient to the will of the great travelers, were they minded to pass that way.

That is to say, the confederation wanted a puppet, and in Leopold they found a dreamer, which served as well.

That glittering bait, a crown, had lured him from his peaceful Osian hills and valleys, and now he found that his crown was of straw and his scepter a stick.
He longed to turn back, for his heart lay in a tomb close to his castle keep, but the way back was closed.

He had sold his birthright.

So he permitted his ministers to rule his kingdom how they would, and gave himself up to dreams.