The two Finnish coastal defence ship participated in Operation Nordwind on 13 September 1941, in which German forces were to take the Estonian islands of Saaremaa and Hiiumaa. A group of Finnish and German ships were to be used in a diversionary operation to lure the Soviet fleet into battle – away from the real invasion force coming up from the south. Another German fleet, including the cruisers , , and , waited further away to join the battle if the Soviets turned up; however, the northern fleet remained unnoticed and an order was given to turn around when they had reached a point some south of Utö. The formation was led by minesweepers, but some mines had escaped being swept. The crew of "Ilmarinen" failed to take proper notice of the dragging paravane cable. It is likely that the ship had caught one or two sea mines in the paravane, and when the ship turned, the mines struck the bottom of the hull and exploded. The explosion blew a large hole in the ship, which soon developed a strong list and keeled over. The ship sank in just seven minutes. Only 132 men of the crew survived, and 271 were lost, most of them trapped inside the hull. Fifty-seven were rescued by the patrol boat "VMV 1", which had maneuvered to the capsized hull and took on as many of "Ilmarinen"s crew as she could. During this time she too was at great risk of being obliterated if "Ilmarinen"s magazines had ignited.