October Crisis (1970)

"The October Crisis began on the 5th of October, 1970 with the kidnapping of James Cross, the British trade commissioner in Montréal, by members of the Front de Libération du Québec (FLQ). It rapidly devolved into the most serious terrorist act carried out on Canadian soil after another official, Minister of Immigration and Labour, Pierre Laporte, was kidnapped and killed. The crisis shook the career of recently elected Liberal Premier Robert Bourassa, who solicited federal help along with Montréal Mayor Jean Drapeau. This help would lead to the only invocation of the War Measures Act during peacetime in Canadian history."--The Canadian Encyclopedia

In response to the crisis, the Mapping and Charting Establishment of the Department of National Defence was ordered to rapidly update many of the map sheets in the Canadian National Topographic Series covering the Province of Quebec--a task that under normal conditions would have been undertaken by the Canadian Government's civilian mapping agency, the Surveys and Mapping Branch of the Department of Energy, Mines and Resources. The MCE revised maps are very distinctive in apearance as the updated features are overprinted in purple. Each map bears the disclaimer: "The overprinting to update this map has been office compiled from best available plans and aerial photography. The information has not been field checked and is therefore subject to interpretation errors," indicating the speed and urgency in which they were prepared.