"Guderian - who was happy to describe himself as Liddell Hart's disciple and pupil and even translated his works into German - had learned his lessons well. In September 1939 his panzers were unstoppable. The Poles did not, as legend has it, attempt cavalry charges against them, though mounted troops were deployed against German infantry, but they lacked adequate motor transport and their tanks were fewer and technically inferior to the Germans'. Moreover, like the Czechs before them, the Poles found Anglo-French guarantees to be militarily worthless. At the Battle of Bzura they mounted a desperate counteroffensive to hold up the German assault on Warsaw, but by September 16 their resistance was crumbling. By the 17th the Germans had reached the fortress at Bresc (Brest) on the River Bug. On September 28 Warsaw itself fell. Eight days later the last Polish troops laid down their arms. The entire campaign had lasted barely five weeks. The Poles had fought courageously, but they were outnumbered and outgunned."