The offensive commenced after the 2nd Belorussian Front had successfully taken Grodno and Bialystok in the Belostock Offensive.
The Front was issued with new objectives at the end of July, being ordered to move on Łomża (German: Lomscha) and Ostrołęka (German: Scharfenwiese) and to enlarge bridgeheads over the Narew river in preparation for a further advance into East Prussia.
The defenders were somewhat aided by fortifications from previous eras, including a major Imperial Russian-era fortress complex at Osowiec on the Biebrza River that was a scene of a siege in 1915 (February to August) during the First World War, and which was partly demolished by Wehrmacht troops in 1939 before its surrender to the Red Army. There were also substantial Soviet border fortifications remaining from the Molotov Line located 20 km West of the old fortress.
On June 22, 1944, the Soviets launched their main summer offensive (Operation Bagration) in Belarus. Involving 2.5 million soldiers and over 6,000 tanks, the offensive sought to destroy Army Group Center while also preventing the Germans from diverting troops to combat the Allied landings in France. In the ensuing battle, the Wehrmacht suffered one its worst defeats of the war as Army Group Center was shattered and Minsk liberated.