Following the swift German advance into eastern France through Belgium and Luxembourg in August 1914 under the Schlieffen plan, progress quickly slowed as both sides suffered unexpectedly heavy casualties. A series of offensives and counteroffensives yielding minimal ground forced a race to the sea as both sides attempted to outflank each other. With the approach of winter the intricate western front trench system, stretching from Switzerland all the way up to the Belgian coast, became more established as stalemate set in. To the north, the Allied defence consisted primarily of Belgians and the troops of the British Expeditionary Force, whilst the French held the front to the south behind their pre-existing border fortifications. Surprisingly, December saw a marked downturn in fighting in many areas of the front as soldiers on both sides of the trenches put down their weapons and engaged in Christmas festivities.
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