text: drift ice the alternation between the difficulties of navigating and maintaining convoy cohesion in constant darkness in winter convoys or being attacked around-the-clock in constant daylight in summer convoys
  Notable convoys
  The "Dervish" convoy assembled at Hvalfjörður and sailed on 21 August 1941. It arrived at its destination, Archangel, ten days later. The convoy was relatively small and consisted of only six merchant ships: Lancastrian Prince, New Westminster City, Esneh, Trehata, the elderly Llanstephan Castle, the fleet oiler Aldersdale and the Dutch freighter Alchiba. The Commodore was Captain JCK Dowding RNR. The escorts comprised the ocean minesweepers HMS Halcyon, Salamander and Harrier, the destroyers HMS Electra, Active and Impulsive and the anti-submarine trawlers HMS Hamlet, Macbeth and Ophelia. As evidence of Churchill's astute mastery of propaganda, on board Llanstephan Castle were two journalists and the artist Felix Topolski.
  On 30 May 1942, the surviving ships of Convoy PQ 16 arrived, most ships to Murmansk and eight to Archangel; the convoy was such a success in terms of the war stores delivered that the Germans made greater efforts to disrupt the following convoys. The crane ships from PQ 16 including SS Empire Elgar stayed at Archangel and Molotovsk (now Severodvinsk) unloading convoys for over 14 months.