In his book "1658: tåget över bält" (), the Swedish historian Lars Ericson Wolke explained that several factors led to Charles X Gustav's victory in his first war with Denmark. On paper, the armies of Denmark and Sweden were relatively equal, though the Danish army and navy were slightly stronger. The Swedish army, however, was more combat-experienced, and its command was significantly more determined and ruthless. From a purely strategic and operational point of view, Charles X Gustav's decision to launch a campaign against Denmark was an unreasonable one, since he had not finished his ongoing campaign in Poland. But for the king and the Swedish command, Denmark was a higher priority than Poland, and the march towards Jutland gave Sweden an opportunity to withdraw from what they called the "Polish swamp" with their honor intact.