"Middlesex County" recommissioned on 27 September 1961 and soon established a pattern of alternating operations between the Virginia Capes area and the Panama Canal Zone training marines and soldiers in the techniques of modern amphibious warfare. In the spring of 1962 she participated in "Operation DEMOLEX" and amphibious demonstrations for President John F. Kennedy at Onslow Beach, North Carolina. That fall she was awarded the battle efficiency "E" for being the top ship of 16 activated for the Amphibious Force during 1961.