During the early stages of the Battle of the Border the northern Army Łódź was partially surrounded by quickly advancing German forces. Army Kraków, attacked by the German 14th Army under the command of General Wilhelm List, was forced to retreat to protect its flanks from 2 September onwards. A careful tactician, General Szylling followed the strategy of 'retreat to fight another day' instead of engaging the superior enemy. General Szylling, despite the increasingly difficult situation for the Polish forces, was able to retreat successfully towards the city of Lublin, following his orders and avoiding several German attempts to surround him. On 19 September Szyling's forces joined with Army Lublin of General Tadeusz Piskor in the Battle of Tomaszów Lubelski, the second largest tank battle of the campaign. Polish forces followed the plan of General Piskor, but the German defences proved too strong and the majority of Polish forces, including the headquarters of both generals, were encircled and surrendered on 20 September.