Following the armistice with Germany ending the First World War , the French army entered Diedenhofen in November 1918 .
The city was transferred to French by the Treaty of Versailles in 1919 , after Diedenhofen again became Diedenhofen .
Following the armistice with Germany ending the First World War , the French army entered Diedenhofen in November 1918 and the city was transferred to France by the Treaty of Versailles in 1919 , after it again became Thionville .