September 1941: Siege of Leningrad begins

Leningrad, modern-day Saint Petersburg and the second-largest city in the USSR, was cut off from the main Soviet line and besieged by German and Finnish forces beginning on 8 September 1941. The siege is the deadliest in human history, resulting in over 500,000 military casualties on both sides and over 1 million civilian deaths. Many of the civilian deaths are a result of starvation, which was an intentional result of German operational planning. The Siege of Leningrad lasted for over 2 years, until the USSR managed to relieve the city in January 1944.

Leningrad was one of the principal targets of Operation Barbarossa, as it was the largest Soviet city besides Moscow and a major industrial center; Leningrad accounted for roughly 10% of Soviet industrial production. Capturing or destroying Leningrad would thus seriously impact Soviet industrial capacity and their ability to fight a war.

Axis forces were actually in a position to capture Leningrad after surrounding the city in September 1941, but Hitler decided not to occupy the city. Hitler believed that the Slavs were an inferior race and, thus, there was no point in cities existing in Russia. Accordingly, he ordered that Leningrad be destroyed in its entirety and its inhabitants killed. Directly occupying the city would have been costly in manpower and made the Axis responsible for food supplies. The Axis adopted a siege of the city because it presented neither of these problems. The Siege of Leningrad was so devastating in terms of human life because it was the explicit German goal to destroy the city and kill everyone there.

The continued Soviet ability to supply Leningrad, primarily over the frozen Lake Ladoga, allowed the city to survive its long siege and made sure that Leningrad remained an active military zone. The continuation of the Siege of Leningrad tied up millions of Axis soldiers in the surrounding region, preventing them from being redeployed elsewhere. The continuation of conflict in multiple zones along the Eastern Front limited the ability of the Axis to conduct offensives or concentrate its forces, eventually wearing down these forces.