In February 1941, Skylark B reported on German ships in Trøndelag, and on export of iron ore from Narvik. In March, there were telegrams on pyrite shipments from Thamshavn, on large numbers of German troops in Mosjøen, on a seaplane base in Hommelvik, and on German gas ships in Trondheim. During spring 1941, telegrams reported high military activity (German troop movements) which later appeared to reflect preparations for the German attack on the Soviet Union. In May 1941, before the German battleship "Bismarck" battle, Skylark reported to SIS that three destroyers had arrived in Trondheim. Skylark B also facilitated communication between London and Trondheim regarding the production of heavy water at Vemork.