Following the Battle of Caporetto, which took place from 24 October to 19 November 1917, a British and French Expeditionary Corps was sent to northeast Italy in order to reinforce the Italian front line.
When the Italian Front stabilized a month later, General Émile Fayolle, who was the new commander in chief of the French troops supporting the Italians, granted leave to soldiers who had previously fought on the Western Front so that morale would improve in the wake of the 1917 French Army mutinies.
At the end of November 1917, a rail transport plan was organized to transport the French soldiers from Vicenza, an Italian city, to railway stations in France.

On the night of 12-13 December 1917, military train number 612 was returning from Italy filled with French soldiers who had spent a month helping Italian troops.

After passing through the Mont Cenis Tunnel the train reached Modane station, where two additional cars were coupled to the train before the journey onward to Chambéry.
From there they were to disperse to join their families throughout France for 15 days of leave covering the year-end holidays.
The train stopped at Modane for 1 hour to allow other trains to pass.
Most of the officers left the train during this stop, to take the Modane-Paris express.
Following the Battle of Caporetto, which took place from 24 October to 19 November 1917, a British and French Expeditionary Corps was sent to northeast Italy in order to reinforce the Italian front line. When the Italian Front stabilized a month later, General Émile Fayolle, who was the new commander in chief of the French troops supporting the Italians, granted leave to soldiers who had previously fought on the Western Front so that morale would improve in the wake of the 1917 French Army mutinies. At the end of November 1917, a rail transport plan was organized to transport the French soldiers from Vicenza, an Italian city, to railway stations in France.
On the night of 12-13 December 1917, military train number 612 was returning from Italy filled with French soldiers who had spent a month helping Italian troops.
After passing through the Mont Cenis Tunnel the train reached Modane station, where two additional cars were coupled to the train before the journey onward to Chambéry. From there they were to disperse to join their families throughout France for 15 days of leave covering the year-end holidays. The train stopped at Modane for 1 hour to allow other trains to pass. Most of the officers left the train during this stop, to take the Modane-Paris express.
Saint-Michel-de-Maurienne derailment