The First World WAR began in 1914 and was fought in many different locations. Three of the most significant battle sites were the Yser, Marne, and Ypres. The Battle of Yser was fought in Belgium in October 1914, when German forces attempted to invade the country. The Battle of the Marne was fought in France in September 1914, and was a decisive victory for the Allies. The Battle of Ypres was fought in Belgium in April 1915, and was a major Allied victory. Additionally, the Battle of the Masurian Lakes was fought in East Prussia in September 1914, and was a German victory. Finally, the assassination of Archduke Franz Ferdinand in Sarajevo in June 1914 is widely considered to be the spark that ignited the WAR.