Mourmelon-le-Grand is a commune in the Marne department in north-eastern France. The camp de Châlons, also known as camp de Mour…Mourmelon-le-Grand is a commune in the Marne department in north-eastern France. The camp de Châlons, also known as camp de Mourmelon, is a military camp of circa 10,000 hectares near Mourmelon-le-Grand. It was created at the behest of Napoleon III and opened August 30, 1857 during the Second French Empire.