in which country/region did the battle of radzymin take place?
Poland
Battle of Radzymin (1920)
The battle occurred near the town of Radzymin, some north-east of Warsaw, between August 13 and 16, 1920. 
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Battle of Radzymin (1920) [SEP] Introduction
The Battle of Radzymin () took place during the Polish–Soviet War (1919–21). The battle occurred near the town of Radzymin, some north-east of Warsaw, between August 13 and 16, 1920. Along with the Battle of Ossów and the Polish counteroffensive from the Wieprz River area, this engagement was a key part of what later became known as the Battle of Warsaw. It also proved to be one of the bloodiest and most intense battles of the Polish–Soviet War. The first phase of the battle began on August 13 with a frontal assault by the Red Army on the Praga bridgehead.