the earlier 0.75 inches to 0.5 inches. The Fletcher-class destroyers were equipped with a Mark 4 or Mark 12 fire-control radar on the roof of the Mark 37 director. A SC-2 early-warning radar and a SG surface-search radar were fitted on the foremast. For anti-submarine work, the ships used a QC series sonar. Construction and service history Construction of Johnston, named after Lieutenant John V. Johnston, an officer of the US Navy during the American Civil War, began with the laying of her keel at the Seattle-Tacoma Shipbuilding Corporation's yard on 6 May 1942. Her launch, sponsored by Marie S. Klinger, Lt. Johnston's grandniece, took place on 25 March 1943. Johnston was finally commissioned into the United States Navy and placed under the command of Lieutenant Commander Ernest E. Evans on 27 October 1943. She then sailed to the Puget Sound Naval Shipyard and fitted out into early November. On 15 November, Johnston sailed for San Diego, California. From 19 November to 1 January 1944, Johnston put out to sea for her shakedown cruise and her crew trained with fleet units near San Diego. Gilbert and Marshall Islands campaign On 13 January 1944 Johnston set sail for Hawaii with a US Navy squadron led by Rear Admiral Jesse B. Oldendorf and arrived 21 January. From there, Johnston sailed to join the ongoing campaign against the Japanese Empire in the Gilbert and Marshall Islands. She arrived by 29 January and was assigned to Fire Support Group 53.5 under Oldendorf. On 30 January, she screened for the cruisers , , , and the battleship as they provided naval gunfire support for American forces in the Wotje Atoll. Johnston sailed for the Kwajalein Atoll, where from 31 January to 3 February she provided gunfire support for American forces attacking Roi-Namur Island. Johnston was reassigned on 5 February 1944 to escort transport ships to the Ellice Islands with destroyers and , and the destroyer-minesweeper . The convoy set sail on 6 February but en route Johnston was ordered to return to the Marshalls for resupply. She arrived on 8 February, refueled, and then set sail for Kwajalein on 10 February. Her arrival was delayed until the next day after jellyfish clogged and overheated her condensers. Almost as soon Johnston arrived, she was tasked with investigating a sighting of a Japanese submarine. No such vessel was detected. Early on 12 February, Japanese bombers attacked Roi-Namur,