Why the successful German advance stopped in Dec 1941?

The successful German advance during Operation Barbarossa halted in December 1941 primarily due to the harsh winter conditions, which the Wehrmacht was unprepared for, leading to equipment failures and diminished troop morale. Additionally, the fierce resistance from the Soviet Red Army, bolstered by reinforcements and improved tactics, played a crucial role in halting the German advance. The combination of logistical challenges, overstretched supply lines, and the Soviets' ability to launch counteroffensives further contributed to the stalling of the German offensive.