Field Marshal Lennart Torstenson had unexpectedly marched into Jutland in September 1643 (see Torstenson War). While engaged in operations there, an Imperial army under the command of Count Matthias Gallas ventured north towards Jutland to trap the Swedish army there and destroy it. The Emperor had received requests from Denmark for help, as well as assurance that the Swedish forces were wore down and therefore a fairly easy target. However, since Torstenson thought of Gallas' approaching army of about 15,000 men as a threat to the important Swedish strongholds on the German Baltic coast, he turned his army around and headed south to engage the enemy.