 Complete the following phrase:  The German command wanted to keep the railway lines at all costs, so that this army could return to Germany, and there were only two roads: through Białystok and Grajewo to East Prussia or through Warsaw to Berlin. Józef Piłsudski chose to avoid the option of German Army passing through the center of the country and be withdrawn by road through Białystok. Therefore, Białystok had to be left in German hands. On 5 February 1919, another Polish-German agreement was signed, so that where the German army withdrew, Polish troops could enter, because of the 