 Complete the following phrase:  The He 111 was committed to operations in the Arctic Ocean against the Arctic convoys traveling to the Soviet Union from North America and the United Kingdom. One notable action involved I.KG 26 attacking Convoy PQ 17 in June 1942. I.KG 26 and its He 111s sank three ships and damaged three more. Later, III.KG 26 helped Ju 88s of III.KG 30 based at Banak sink several more ships. Some 25 out of 35 merchant ships were sunk altogether. 