Battle of Łomża (7–10 September 1939) was a series of armed engagements during the Nazi German and Soviet Invasion of Poland. The battle took place in and around the town of Łomża, on both sides of the Narew River. Polish forces successfully held a series of pre-First World War forts from repeated German attack before being forced to withdraw due to the position becoming untenable following their losses at the Battle of Wizna and .