Are you referring to World War I or World War II?
In World War I, Germany was the reason for the opening of the Western Front, by the invasion of Belgium in order to attack France.
In World War II, Germany, again, was the reason for the opening of the Western Front. First, they attacked Denmark and Norway (which would be more considered a Northern Front) which was the first contact of German and Allied troops (the British deployed into Norway, but retreated). The Germans then attacked the Benelux countries and France, all falling in a matter of weeks.
In both world wars, the initial front was the Eastern Front (on a German standpoint).
French North Africa : Operation Torch .
The Normandy Invasion opened the Second Front in Europe, putting Hitler in a vise between Russian forces advancing from the East and the Anglo-French-American forces in the West.
Stalin wanted the Allies to open a second front in Europe to releive pressure from his advancing army. If a second front was opened Hitler would have to split his forces and deal with two prongs that were advancing on Berlin and the Rhine, or the production heart of Germany. If either of these were taken Hitler would lose the war. The second front was made to put more pressure on Hitler and end the war quicker.
Teheran
During World War II, the Second Front long-desired by the Allies was finally opened in 1944 in western Europe. This additional front against Germany was started with the successful amphibious invasion -- code-named 'Operation Overlord' -- of Normandy, located in the north central portion of France along the Atlantic coast.
It opened an Allied front in Europe.
Joseph Stalin needed a second front opened to draw off German Forces and to ease the pressure that was being placed on the USSR.
The Soviet Union wanted the US to open up a second front.
D-Day in June 6,1944.
What is a front door attack
Josef Stalin, leader of the Soviet Union
joseph stalin