a base of operations (44 km along the front and 4 to 10 km deep) on the west bank of the Oder River, near the city of Küstrin (60 km east of Berlin; now Kostrzyn, Poland), seized by the troops of the First Byelorussian Front (commanded by Marshal of the Soviet Union G. K. Zhukov) in January-March 1945 during the Great Patriotic War (1941–45).
At first on January 31 an advance detachment of the Fifth Shock Army seized a base northwest of Küstrin, and on February 3 troops of the Eighth Guards Army seized three small bases south of Küstrin. Up to the middle of February fierce battles were fought with the enemy, who tried to destroy the bases. The Fifth Shock Army succeeded in widening the base of operations to 27 km along the front and to a depth of 3 to 5 km, and the Eighth Guards Army succeeded in consolidating its three bases into one (with 14 km along the front and to a depth of 3 to 5 km). In March the Soviet troops captured Küstrin and consolidated the whole captured territory into one base of operations. By April 16 attack positions had been built up at the Küstrin base of operations for the main assault grouping of the First Byelorussian Front (Forty-seventh Army, Third and Fifth Shock armies, Eighth Guards Army, and First and Second Guards Tank armies) to enable it to deliver the main attack during the Berlin operation of 1945.