With all his good qualities, Frederick was not a man to recognize fully his own limitations and that of his country. But he rightly regarded the accession of Charles X of Sweden on 6 June 1654 as a source of danger to Denmark. He felt that temperament and policy would combine to make Charles an aggressive warrior-king: the only uncertainty was in which direction he would turn his arms first. Charles's invasion of Poland in July 1655 came as a distinct relief to Frederick, even though the Polish War was full of latent peril to Denmark. Frederick was resolved upon a rupture with Sweden at the first convenient opportunity. When "Rigsdagen" assembled on 23 February 1657, it willingly granted considerable subsidies for mobilization and other military expenses. On 23 April he received the assent of the majority of "Rigsraadet" to attack Sweden's German dominions. In the beginning of May, the still pending negotiations with that power were broken off, and on 1 June Frederick signed the manifesto justifying a war, which was never formally declared.