He was first a supporter of the Unitary State with Holstein, but during the First War of Schleswig he switched to a pro-Danish policy, and in 1850 he enacted a temporary law removing the customs duties between Denmark and Schleswig, and later the same year, he enacted a similar law abolishing the Danish-Schleswig customs border altogether.
[1] In January 1851, Sponneck traveled to Berlin to negotiate with Prussia and Austria, trying to establish a peace settlement that maintained the Danish/Schleswig/Holsteinish union while securing extra close ties between Denmark and Schleswig.
He was unable to secure a lasting agreement, and he abandoned his pro-Danish sympathies and returned to defending the pre-war Unitary State.
[4] His popularity dropped even lower when he in 1854 proposed a return to absolutist royal rule in matters relating to Danish-Holsteinish affairs.
Sponneck later resigned these positions and became the leader of the newly founded Kjøbenhavns Handelsbank and chairman for the insurance company, Danmark.