The 'Brest Fortress Defensive Operation' was the Soviet defence of Brest-Litovsk during the first week of 'Barbarossa' (22/30 June 1941).

The area round the fortress of Brest, built in the 19^th century, was the site of the 'Battle of Brześć Litewski', in which the area was seized from the Poles by the Germans during 'Weiss' (i) in September 1939. By the terms of the Non-Aggression Pact signed between Germany and the USSR in August 1939, however, the territory around Brest as well as 52% of what was currently eastern Poland was assigned to the USSR, so in the summer of 1941 the Germans had once again to capture the fortress, on this occasion from the Soviets rather than the Poles.

The Germans planned to seize Brest and its fortress, which lay in the path of Generalfeldmarschall Fedor von Bock’s Heeresgruppe 'Mitte' and controlled the crossings over the Bug river as well as the rail and road lines linking Warsaw and Moscow, during the first hours of 'Barbarossa'. Lying in the area of General Major Aleksandr A. Korobkov’s 4^th Army within General Dmitri G. Pavlov’s West Front, the area was held by something more than 9,000 Soviet soldiers of Polkovnik Mikhail Popsuy-Shapko’s 6^th Division and General Major Ivan S. Lazarenko’s 42^nd Division, the 17^th Frontier Guards Detachment of the NKVD Border Troops, and various smaller units including the garrison hospital and a medical unit inside the fortress.

The German attack was vested in the 17,000 men of Generalleutnant Fritz Schlieper’s 45^th Division as well as 3,000 men and part of the artillery of Generalmajor Kurt Kalmukoff’s 31^st Division, Generalleutnant Hans Behlensdorff’s 34^th Division and Generaloberst Heinz Guderian’s 2^nd Panzergruppe.

The 'Barbarossa' onslaught took the Soviets by complete tactical and operational surprise on 22 June, and Brest immediately became the location of the first major fighting between the German and Soviet forces. The area came under artillery bombardment as soon as 'Barbarossa' began, and this immediately inflicted heavy matériel and personnel losses. Fierce battles were fought on the border, in the city of Brest and in the fortress itself as the Germans began their assault on the fortress 30 minutes after the start of the bombardment. The Soviets were unable to create any continuous front, but instead held isolated strongpoints, of which the most important was the fortress itself. While some Soviet troops managed to fall back to the east from the fortress, most were trapped as the Germans encircled the area.

Despite the fact that they had the advantage of surprise, the Germans failed in their first attempt to take the area with infantry alone, and in the process suffered heavy losses. Some 281 Germans were killed in the first day of the battle for the fortress. Heavy fighting continued for another two days, and by the evening of 24 June the Germans had lost 368 dead, while the Soviets had lost between 4,000 and 5,000 men taken prisoner. On 25/26 June fighting continued mainly in the citadel, and by the evening of 26 June the Germans had seized most of the northern Kobrin fortification with the exception of the East Fort, which was then bombed twice on 29 June, forcing its surviving 360 men to surrender.

Although in the first hours of the battle the Soviet troops had been stunned by the surprise attack, and were outnumbered, short of supplies, and almost immediately cut off from the outside world, many of them held out much longer than the Germans expected. The Germans deployed artillery, rocket-launchers and flamethrowers in support of their infantry. On 24 June, by which time the Germans had taken parts of the fortress, some Soviet troops were able to join forces and co-ordinate their defence under the command of Major Ivan N. Zubachyov, supported by the political commissar Yefim M. Fomin. On 26 June small Soviet forces tried to break out from the siege but were unsuccessful and in the process sustained heavy casualties. It is probable that Zubachyov and Fomin were captured on this day.

Late on 30 June the Soviets decided to abandon Brest, and the main surviving strength of the defence broke out of the German encirclement on 2 July. The fighting had effectively ended on 30 June, by which time the Germans had lost 482 men killed, and taken 7,000 Soviet prisoners. The Soviet nine-day defence defence had been notable but in effect unnecessary, for the Germans had achieved their operation objective, namely the seizure of the paved road to Moscow, the important railway line, and the bridges over the Bug river, on 22 June.