Camp Conlie was one of eleven military camps established by the Republican Government of National Defense under Léon Gambetta during the Franco-Prussian war. It became notable because of events which have led to it being described as a "concentration camp", in which troops from Brittany were supposedly incarcerated and persecuted. This became a significant atrocity story within Breton nationalism.
After the defeat of French forces at the Battle of Sedan, and the fall of the monarchy of Napoleon III, a new republic was proclaimed. The new government decided to form a new army and continue the war. Major General Émile de Kératry was made responsible for establishing a camp at Conlie in the region of Le Mans and mobilized volunteers from the west of France to form an "army of Brittany". The mobilized quota from the five departments of Brittany was 80,000 men. It was intended that these troops would be equipped with the weapons left over from the American Civil War, but these promised weapons failed to materialize.
Because of a history of anti-republicanism in Brittany, Gambetta doubted the reliability of these troops, and Kératry was suspected of separatist inclinations.
The huts were not built when the soldiers arrived. In consequence, they were housed in emergency tents. Bad weather and the recently ploughed land quickly created a quagmire in which it was difficult to move. A lack of instructors, equipment and supplies caused frustration. Disease caused significant mortality.
Rumours about the camp began to circulate in Brittany. As visiting English journalist Ernest Vizetelly noted,
The most appalling rumours were current throughout Brittany regarding the new camp. It was said to be grossly mismanaged and a hotbed of disease. I visited it and prepared an article which was printed by the Daily News ...So far as the camp's defences and the arming of the men within it were concerned my strictures were fully justified.