Second Battle of the Marne
1918 CE.
Shown on the map at 49.083°, 3.667°.
The Second Battle of the Marne (French: Seconde Bataille de la Marne; 15 – 18 July 1918) was the last major German offensive on the Western Front during the First World War. The attack failed when an Allied counterattack, led by French forces and supported by several hundred Renault FT tanks, overwhelmed the Germans on their right flank, inflicting severe casualties. The German defeat marked the start of the relentless Allied advance which culminated in an armistice with Germany about 100 days later.
Text from the Wikipedia article Second Battle of the Marne, licensed CC BY-SA 4.0.