Joseph Joffre was Commander-in-Chief, a position for which he had been designated since 1911. While serving in this position, Joffre was responsible for development of the Plan XVII the mobilisation and concentration plan for the offensive strategy against Germany, which proved a costly failure. Joffre was thought to be the 'Savior of France' due to his serenity and a refusal to admit defeat, valuable at the beginning of the war, along with his regrouping of retreating Allied forces at the Battle of the Marne. Joffre was effectively relieved of his duties on December 13, 1916, following the heavy human losses at the Battle of Verdun and the Somme, and the defeat of Romania, which appeared for a time to put the Salonika Bridgehead in jeopardy. Due to his popularity, it was not presented to the public as a dismissal when he was promoted to Marshal of France on the same day.