As the close escort and the covering cruiser forces withdrew westward to intercept the presumed German raiders, the individual merchant ships were left without their escorting destroyers. In their ensuing attempts to reach the appointed Russian ports, the merchant ships were repeatedly attacked by Luftwaffe airplanes and submarines. Of the initial 35 ships, only 11 reached their destination, delivering of cargo. The disastrous outcome of the convoy demonstrated the difficulty of passing adequate supplies through the Arctic, especially during the summer period of perpetual daylight.