Erik Gustaf Geijer stated Erik Dahlbergh was "the foremost instigator" behind the king's decision to cross the Belts. Following Geijer, several Danish and Swedish historians made the same assessment of Dahlbergh's role, including Ernst Ericsson, but some, as emphasized by Curt Weibull, highlighted Ulfeldt's role in the campaign. Julius Albert Fridericia and Fredrik Ferdinand Carlson mainly expressed this approach. Writing in 1855, Carlson emphasized how Wrangel and Ulfeldt argued against a march across the ice and almost convinced Charles X Gustav to call off his campaign until Dahlbergh, in a single deliberation, persuaded the king to change his mind. Carlson regarded Charles X Gustav as the man who gave Sweden its natural borders, and as an early proponent of Scandinavism whose war policy strove for the unity of and prosperity for the entire Nordic region. Though he rejected calling Charles X Gustav a proponent of a united Scandinavia, Fridericia was of the same opinion as Carlson that "it was Erik Dahlbergh whose council came to decide the fate of the Nordic nations".