The big ships of the Kriegsmarine in Norway were seldom involved in these attacks, because of the inferiority of German radar technology,[11] 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.