 Complete the following phrase:  As part of Southern, North-Caucasian, Transcaucasian Front, and the 1st and 4th Ukrainian Fronts the 18th Army conducted defensive operations in right-bank Ukraine, participated in Donbass, the Rostov defensive and offensive operations, and in the fight for Caucasus. Based on the experience of the Kerch - Eltigen landing operation, the Army was uniquely identified as 18th Desant Army  for amphibious operations, between 15 February and 5 April 1944 around 