What is the fine-grained topic of the following text: Shortly after the armistice was signed at 11:11 a.m. on Nov. 11, 1918 to end the First World War, the Canadian Pipes and Drums’ 42nd Battalion Royal Highlanders marched into Mons, Belgium announcing to the citizens that they had been liberated from four and a half years of German occupation. Only return the topic.
The liberation of Mons, Belgium by the Canadian 42nd Battalion Royal Highlanders after World War I.