With the German attack on the Soviet Union in June 1941 Britain started to send Arctic convoys with military goods around Norway to support their new ally. In 1942 German forces began heavily attacking these convoys, mostly with bombers and U-boats. The big ships of the "Kriegsmarine" in Norway were seldom involved in these attacks, because of the inferiority of German radar technology, and because Hitler and the leadership of the "Kriegsmarine" feared losses of these precious ships. The most effective of these attacks was the near destruction of Convoy PQ 17 in July 1942. Later in the war German attacks on these convoys were mostly reduced to U-boat activities and the mass of the allied freighters reached their destination in Soviet ports.