the town by claiming that a Brandenburg patrol was after him. Once the gates were opened for him, he led a charge of 1,000 dragoons against the city and the rest of the army soon followed. He was 69 years old at the time. Once Derfflinger had forced the Swedish garrison from Rathenow, Wrangel pulled back his troops toward Havelberg. His progress was greatly impeded by marshes that the summer rains had turned treacherous. On June 17, the Brandenburgian troops reached Nauen. Meanwhile, Frederick William's advance parties, under the command of Colonel Joachim Hennings and guided by locals, blocked the exits of the area. The Swedes, who had planned to cross the Elbe river in order to join forces with Brunswick troops, were forced back to their last position at Fehrbellin. Battle The Swedish commander, Wrangel, found himself hemmed in by a destroyed bridge over the Rhin river by the town of Fehrbellin. Impassable marshes on both flanks left Wrangel little choice but to give battle south of the nearby village of Hakenberg while his engineers repaired the span. A total of 6,000–7,000 Brandenburgers with 13 cannons faced 7,000 Swedes with 28 guns. Wrangel omitted to secure the surrounding heights, and Frederick William and Derfflinger, by placing their guns on a series of low hills to his left while the Swedes had only swamps to their flanks and a river behind them, gained a decisive tactical advantage. These guns opened fire around noon on the 18th and caused heavy casualties on the Swedish right flank. Wrangel, now fully aware of the threat, attempted several times to wrest control of the hills but was stopped each time by the Brandenburgian cavalry. This continued for some hours until Frederick William had his main attack press the right flank of the Swedes, eventually causing their cavalry to flee, thereby exposing their Dalwig Guard infantry to a flank attack led by Prince Frederick II of Hesse-Homburg. The Brandenburgian cavalry then turned and routed a regiment of Swedish infantry. The Swedish right however had held up long enough though for the Fehrbellin bridge to be repaired and Wrangel was able to get a large portion of his army across before darkness fell. Frederick William rejected all his officers' suggestions to shell the town. The Brandenburg troops lost about 500 men. Wrangel's forces lost slightly more than the Brandenburgers but it is unclear exactly how many.