High Quality Content by WIKIPEDIA articles! If Day (Si un jour ... in French) was a simulated Nazi invasion of the Canadian city of Winnipeg, Manitoba, and surrounding areas on February 19, 1942, during the Second World War. It was organized by the Greater Winnipeg Victory Loan organization, which was led by prominent Winnipeg businessman J. D. Perrin. The event was the largest military exercise in Winnipeg to that point.