Mortier received orders to maintain the blockade with Grandjean's division and march with his other forces to assist in the Siege of Kolberg. After Mortier left, the Swedes drove Grandjean's outnumbered troops from their siege lines. Grandjean fell back to Anklam where he was attacked again on 3 April and compelled to withdraw southeast to Stettin on the Oder River, reaching there on 7 April. Mortier retraced his steps and by 13 April had assembled 12,000–13,000 men at Stettin, the same as the Swedes. In rainy weather, Mortier drove his adversaries back to Anklam and after a scuffle, the Swedes retreated to the north bank of the Peene on 17 April. Franco-Allied troops under Guillaume Brune successfully concluded the Siege of Stralsund on 20 August 1807.