The Eastern Front
The fighting on the Eastern Front didnt start until later in the war. Before the war started Stalin and Hitler had signed a non-agression pact. However Hitler still attacked. The Soviets were not prepared for the attack, so Hitler took over very quickly. The Soviets made a stand at Stalingrad and repelled the Germans.
Germany was still focused on the Western Front mainly, but after the battle of Stalingrad where the Soviets won the battle, Germany was convinced it would take a massive attack on the Eastern Front would put the Soviets out of the fight for good. Hitler believed that after losing over a million troops at Stalingrad that the Soviets wouldn't be able to stand his counter-strike. He sent a massive force to stop the Soviet's advance.
The Eastern Front borders
When the German forces arrived, they were greeted with the newly reinforced Soviet army. The Germans weren't prepared for the Soviet reinforcements, and were quickly defeated, Hitler's retreating army had already lost 500,000 men and 1,000 tank. The Soviets has also suffered many casualties, but the important thing was that the Germans were now on the defensive. The Soviets quickly forced thier way into German terretory and past the Eastern Front borders. They took control of the eastern part of Germany, and then turned thier attention towards Berlin. The Soviet army fired the first artilary shells early in the morning, they used there advantage of surprise to quickly overrun Berlin. The Soviets captured Berlin and brought an end to the fighting in Eurpoe.