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. Robert Nivelle, who began the war as a regimental colonel, was appointed Commander-in-Chief. However, after the failure of the Nivelle Offensive in April 1917 he was removed from his position and appointed Commander-in-Chief in North Africa. On May 15, 1917, Philippe Pétain was made Commander-in-Chief after a few weeks as Army Chief of Staff. The French Army Mutinies had begun during that period, and he restored the fighting capability of the French troops by improving front line living conditions, and conducting only limited offensives. In the Third Battle of the Aisne, fought in May 1918, French positions collapsed due to the local commander General Duchene's defiance of Pétain's recommendation of defence in depth, and Petain's pessimism saw him subordinated to the Supreme Allied Commander Ferdinand Foch. Western Front Germany marched through neutral Belgium as part of the Schlieffen Plan to invade France, and by August 23 had reached the French border town of Maubeuge, whose true significance lay within its forts. Maubeuge was a major railway junction and was consequently a protected city. It had 15 forts and gun batteries, totaling 435 guns, along with a permanent garrison of 35,000 troops, a number enhanced by the British Expeditionary Force. The BEF and the French Fifth Army retreated on August 23, and the town was besieged by German heavy artillery starting on August 25. The fortress was surrendered on September 7 by General Fournier, who was later court-martialed, but exonerated, for the capitulation. The Battle of Guise, launched on August 29, was an attempt by the Fifth Army to capture Guise, they succeeded, but later withdrew on August 30. This delayed the German Second Army's invasion of France, but also hurt Lanrezac's already damaged reputation. The First Battle of the Marne