The term of a Canadian Parliament is limited by the constitution to a maximum of five years. And, there must be a sitting of Parliament and each provincial legislature at least once every year. The House of Commons can decide to extend the term of Parliament for special circumstances, such as when there is a war, an invasion of Canadian territory, or a rebellion somewhere in Canada. This happened once in Canadian history when the First World War broke out. Six years went by between the federal elections of 1911 and 1917.
