When did establishing a second major front in Europe happen?

Answer 1

In World War II, a second major front (the Western Front) was opened by the Germans through the Schlieffen Plan. Germany mobilized through neutral Belgium to attack France, when already being involved in the Eastern Front with Russia. The Eastern Front eventually closed when Russia dropped out due to internal problems. In addition, the Russians never truly posed a threat to Germany as they were weak at this time. Germans obliterated Russian troops, most significantly in the Battle of Tannenburg. However, the Western Front was described as deadly stalemate, where little advancements took place. The Germans mainly fought both the French and British, and were generally winning until the later months of the war, where they attempted and failed to breakthrough the Allied lines. In addition, the Americans entered the war and supplied a million more men to the Allies, facing Germany with an endless supply of troops. This gave the Allies a sure victory.

In World War II, a second major front was opened by the Germans again, but this time it was the Eastern Front. World War II started with the invasion of Poland, which is on the Eastern Front, but the early Eastern Front never stood a chance against Germany. Germany then attacked Norway and Denmark, which could be considered either the Northern or Western Front, but they conquered these countries quickly as well. They then turned towards the Lowland countries and France, where they fell in a little over a month total. It was then the UK versus Germany, but Germany was unable to break into British land. Having conquered all of Western Europe but the British Isles, the Germans then opened the Eastern Front against their acquaintances (not allies, and not enemies, then), the Soviets (Russians). However, the USSR was much more prepared for war than in World War II. Although the Germans quickly advanced to Moscow and millions of Russians died, the Soviets prevailed and pushed the Germans back into their own land, and eventually reached Berlin before the Allies. At the same time of the Nazi invasion of the Soviet Union, the Americans entered the war. The Americans' first goal was to eliminate Germany from the war to help its ally, the UK, then it would turn towards Japan, the Pacific power for the Axis. When Germany was defeated, the Americans then turned to Japan where they defeated Japan with an atomic bomb just a couple of months after the fall of Nazi Germany.