The Champlin (DD-601) was launched 25 July 1942 by Bethlehem Steel Company, Fore River, Quincy, Mass.; sponsored by Mrs. A. C. Brendel; and commissioned 12 September 1942, Lieutenant Commander C. L. Melson in command.
After escorting a convoy to Argentia,Newfoundland, and another to the Panama Canal Zone, the Champlin sailed from New York 11 December 1942 on her first convoy crossing to Casablanca, returning to New York 7 February 1943. She sailed again on 4 March guarding a convoy which was constantly shadowed by German submarines for 6 days after it passed the Azores As the convoy plodded east, Champlin and the other escorts fought a constant battle to protect it, but Champlin's was the only kill, while the convoy lost three merchantmen before reaching Casablanca. The return convoy which arrived at Boston 15 April was without incident.
Champlin sailed from New York 1 May 1943 with a slow convoy of small craft and support ships which called at Bermuda before arriving at Oran on 26 May. She put to sea again to bring a convoy in from Gibraltar, then took part in training as well as conducting patrols in the western Mediterranean. On 5 July, she cleared Oran for the invasion of Sicily, escorting a convoy to the transport area south of Scoglitti arriving 9 July. Leaving her charges, she sped ahead to join in the pre-assault bombardment the next day, during which she aided in driving off an enemy air attack, she answered the request from shore for a bombardment of the village of Camerina, so successfully that the enemy there surrendered.
Champlin left Sicily guarding a convoy for Oran and New York, arriving 4 August 1943. Continuing this essential task, she made four more Atlantic crossings on convoy escort duty from New York to North Africa and the British Isles between 21 August 1943