After Jutland the battleship threat from Germany receded somewhat and the danger from mines and submarines grew. Especially vulnerable were the two ports of Murmansk and Archangel in North Russia used by British merchant ships taking materiel to their ally. Mine-sweeping naval trawlers were sent to counter this threat, and two old cruisers were modified to act as repair workshops and headquarters for this flotilla. Agar joined one of them, , executive officer in December 1916. The "Iphigenia" dated from 1892, displaced 3,400 tons and in her early days could make 20 knots.