Charles, like his father Oscar I, was an advocate of Scandinavianism and the political solidarity of the three northern kingdoms, and his friendship with Frederick VII of Denmark, it is said, led him to give half promises of help to Denmark on the eve of the war of 1864, which, in the circumstances, were perhaps misleading and unjustifiable. In view, however, of the unpreparedness of the Swedish army and the difficulties of the situation, Charles was forced to observe a strict neutrality. He died in Malmö on 18 September 1872.