The Mannerheim Line was a defensive fortification built by Finland along its eastern border with the Soviet Union. Named after Finnish military leader Carl Gustav Emil Mannerheim, the line was constructed in the 1920s and 1930s to protect Finland from potential invasions. It included bunkers, trenches, and other military structures designed to withstand attacks. During the Winter War of 1939-1940, the Mannerheim Line became a focal point of resistance against Soviet forces. Despite heavy bombardment and assaults, Finnish troops managed to hold the line for a significant period, showcasing their determination and strategic capabilities in defending their territory.