Von Ungern-Sternberg relinquished command on 21 December 1757 to Gustaf von Rosen, but von Rosen too was forced to lie idle, blockaded by the Prussians. This blockade was lifted by an invading Russian army on 18 June 1758, but von Rosen had grown tired of his thankless task and handed command over to Gustav David Hamilton. Augustin Ehrensvard captured Peenemünde hill on July 27, and Hamilton sent 16,000 men to support the Russians, who were besieging Küstrin. However, after their defeat at Zorndorf he decided instead to march to Saxony to join up with the Austrians. However, he got no further than Neuruppin in Brandenburg. A detachment he sent from there suffered a heavy defeat on 26 September at the Battle of Tornow, but Major was able to reach Fehrbellin with 800 men to defend it from about 5,000 Prussians at a battle fought there on 28 September.