Battle of Radzymin was part of the Battle of Warsaw during the Polish-Bolshevik War.

The final Soviet assault on Polish capital of Warsaw began on August 12 with the attack on the town of Radzymin (only 23 km east of Warsaw), and marked the first phase of the battle. Its initial success prompted Polisch commander, Józef Piłsudski, to hasten the execution of his defence plan by 24 hours.

The first phase of the battle started August 13 with a Red Army frontal assault on the Praga bridgehead. In heavy fighting, Radzymin changed hands several times and foreign diplomats with the exception of British and Vatican ambassadors, hastily left Warsaw. On August 14 Radzymin fell to the Red Army, and the lines of Gen. Władysław Sikorski's Polish 5th Army defending the areas north of Warsaw were broken. The 5th Army had to fight three Soviet armies at once: the 3rd, 4th and 15th. The Modlin sector was reinforced with reserves (the Siberian Brigade, and Gen. Franciszek Krajowski 's fresh 18th Infantry Division--both, elite, battle-tested units), and the 5th Army held out till dawn.

At the same time, the Polish 1st Army under Gen. Franciszek Latinik resisted a Red Army direct assault by six rifle divisions on Warsaw. The struggle for control of Radzymin forced Gen. Józef Haller, commander of the Polish Northern Front, to start the 5th Army's counter-attack earlier than planned.

Radzymin was recaptured on the 15 August and this victory proved to be one of the turning points of the battle of Warsaw. The Polish counterattack proven to be extremly successfull, pushing Soviet armies away from Radzymin and Warsaw, and eventually crippling four Soviet armies.