Battle of Warsaw (1920)
The battle of Warsaw was fought from August 12–25, 1920 as Red Army forces commanded by Mikhail Tukhachevsky approached the Polish capital of Warsaw and the nearby Modlin Fortress. On August 16, Polish forces commanded by Józef Piłsudski counterattacked from the south, disrupting the enemy's offensive, forcing the Russian forces into a disorganized withdrawal eastward and behind the Neman River. Estimated Russian losses were 10,000 killed, 500 missing, 30,000 wounded, and 66,000 taken prisoner, compared with Polish losses of some 4,500 killed, 10,000 missing, and 22,000 wounded.
Siege of Warsaw (1939)
The Army Poznań commanded by General Tadeusz Kutrzeba, and Army Pomorze under General Władysław Bortnowski started an offensive on the left flank of the German forces advancing towards Warsaw. As a result of this offensive that later became known as the Battle of Bzura, German commanders withdrew the 4th Panzer Division and sent it to counter the Polish threat near Kutno. Its positions were replaced by forces of a weakened German 31st Infantry Division. In this sense the desperate attempt to buy time for organising a defence of Warsaw was a success. The defenders of the city were joined by various units of the routed Prusy Army. In addition, several new units were created in Warsaw out of reserve centres of Warsaw-based 8th Polish Infantry Division and 36th "Academic Legion" Infantry Regiment.