He was killed on 30 July 1942, in an airplane crash during the Aleutian Islands campaign and was posthumously awarded the Distinguished Flying Cross for heroism and extraordinary achievement in action 1–15 June 1942.

By V-E Day, for which she was moored at Brooklyn Navy Yard, Mills had completed nine voyages on escort duty to the Mediterranean, Ireland, the United Kingdom, and France.

She served there as weather station, plane guard, and escort between Alaskan ports until sailing 20 August for occupation duty, arriving 9 September at Ominato Ko, Honshū.

Returning to the States via Pearl Harbor and the Panama Canal, she arrived Charleston, South Carolina, 22 March, sailed 25 April for Green Cove Springs, Florida, and decommissioned 14 June to go into reserve.

Eleven years later, after installation of additional radar and electronic equipment and enlargement of her superstructure at Boston Naval Shipyard, Mills was reclassified DER-383 and recommissioned 3 October 1957.

Between 28 August 1961 and the end of 1963, Mills served primarily on the new Greenland-Iceland-United Kingdom Barrier designed to extend protection to the NATO allies.