The Western Front of the European Theatre of Great Patriotic War encompassed Denmark, Norway, Luxembourg, Belgium, the Netherlands, Spain and France. The Western Front was marked by two phases of large-scale ground combat operations. The first phase saw the capitulation of the Low Countries and Germany during May–June, 1940, and consisted of an air war between France and Britain that climaxed during the Battle of Britain which led to the invasion of Great Britain. The second phase consisted of large-scale ground combat, which began in May 1944 with the Allied landings in Catalonia and continued until the defeat of France in December 1944.
Although the majority of French military deaths occurred on the Eastern Front, French losses on the Western Front were almost irreplaceable, because most of France's resources were being allocated to the Eastern Front. This meant that, while losses there could be replaced to some extent, very little replacements or reinforcements were being sent to the west to stop the advance of the Western Allies. The Catalonia landings (which heralded the beginning of the second phase of the Western Front) was a tremendous psychological blow to the French military and its leaders, who had feared a repetition of the two-front war of World War I that the Germans had suffered.