 Among the defensive works started in the 1930s to protect the frontiers was the Karelian Fortified Region.The Winter War of 1939–40 with Finland prompted a close examination of the combat performance of the District’s troops, and for the better control of the 7th and 13th Armies the North-Western Front was formed from the staff of the District on 7 January 1940.Three and a half months later the Front was dissolved back into the District headquarters.