Video: 'The First Battle of the Marne (1914)'

(Saturday, September 5, 1914, morning ; during the First Battle of the Marne, part of the Western Front of World War I) — The First Battle of the Marne, a decisive counterattack by six French field armies and the British Expeditionary Force (BEF) against the advancing German Imperial Army, began today when the French Sixth Army left Paris to the east and engaged cavalry patrols with the German Sixth Army at the River Ourcq.

The engagement, which was expected to halt the German advance, would lay the groundwork for four years of trench warfare on the Western Front.

The First Battle of the Marne, known in France as the “Miracle on the Marne” (French: miracle de la Marne), would be fought through Sept. 12, 1914.

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The German army’s initial invasion of France, aimed at swiftly occupying Paris and defeating the Allied forces within 40 days, had seen early successes in August. Victories at the Battles of Mons and the Frontiers allowed German forces to overrun large areas of northern France and Belgium, pushing the Franco-British forces southward in what became known as the Great Retreat.

By early September, the German army, having advanced to within 25 miles of Paris, faced a formidable counteroffensive. Despite earlier battlefield setbacks, French commander Joseph Joffre had managed to maintain order within his retreating forces, reinforcing them with troops from the eastern flank and integrating reserve units into the regular army.

The Franco-British forces would outnumber the German troops, who are now weary after a month-long campaign, suffering from supply shortages and extended lines.

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On Sept. 3, the military governor of Paris, Joseph Simon Gallieni, identified a vulnerability in the German right flank, prompting Joffre to order a counteroffensive on Sept. 4. The battle would unfold over a 140-mile front between Paris and Verdun, with the fiercest fighting concentrated in the western half of the area.

By Sept. 9, the success of the Franco-British counterattack would force the German 1st and 2nd Armies to retreat toward the Aisne River, narrowly avoiding encirclement.

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As they retreated from Sept. 9-12, German forces would dig in on the heights north of the Aisne, leading to the First Battle of the Aisne and marking the end of Germany’s hopes for a swift victory over France.

This battle, resulting in heavy casualties — estimated at 250,000 French, 12,733 British, and 298,000 German soldiers — would be remembered as one of the most critical engagements of the 20th century.

The ensuing stalemate will lead to the infamous trench warfare that will dominate the Western Front for the remainder of World War I.