The third column marched along the western shore of Lake Lucerne through Bauen and the Isenthal, meeting Lecourbe at Seedorf. The fourth column hiked across the Surenen Pass to reach Erstfeld in the Reuss valley. The fifth column marched from Gadmen across the Susten Pass to Wassen. In the face of this advance, Simbschen withdrew south to the Devil's Bridge where he broke the arch and held his ground. Farther to the west, Gudin's right brigade formed the sixth column which moved south up the Aare valley. According to historian Digby Smith, Gudin's 2,400-strong brigade consisted of the 25th Light Infantry Demi-brigade and a Swiss battalion. Though the Austrian position at Grimsel Pass was very strong, the French surprised their adversaries by taking them in flank. Strauch's 2,600 troops were hustled out of their defenses with heavy losses, especially in the Neugebauer Infantry Regiment Nr. 46. Other Austrian units that were engaged were the Deutsch-Banater Nr. 12 and Warasdiner-St. George Nr. 6 Grenz Infantry Regiments, Wallis Infantry Regiment Nr. 11, Siegenfeld Light Infantry Battalion Nr. 10, Carneville Freikorps, and one squadron of the Erdody Hussar Regiment Nr. 9. The French claimed to have killed and wounded 400 men and captured 500 more, while admitting 60 casualties. An Allied source estimated losses at 200 killed and wounded plus 500 captured.