Armored observation points and 150mm howitzer turrets were installed, while Mutzig was the first German fort with its own electricity generating plant.

[2] The province of Lorraine had been captured during the Franco-Prussian War, prompting an arms race in the form of fixed fortifications on the parts of France and Germany.

The fortress saw no significant fighting during the First World War, and was handed over intact to the French Army after the Armistice of 1918, with the exception of about half of its 105 mm guns, salvaged in 1917 by the Germans.

During the Second World War the fortress was occupied for a time by German artillery and infantry regiments but on June 13, 1940 forces were ordered to evacuate the area and all the guns were decommissioned.

However, part of the Wehrmacht's 215th Infantry Division was in fact in the fortress at the time and more than 70 German soldiers were killed in the Stuka attack.

As the fortress never saw substantial military action, it remains one of the best preserved pre-World War I sites in existence.