After shakedown off the Maine coast, "Herndon" escorted a convoy from New York City to Casablanca, returning to New York 14 May 1943 escorting a tanker. Sailing from Norfolk on 8 June, she reached Algiers on 24 June and prepared for a key role in the Sicilian campaign. As Allied amphibious forces under the overall command of General Dwight D. Eisenhower launched the initial strike at "the soft underbelly of Europe" 10 July 1943, "Herndon" performed antisubmarine patrol duty as well as fire support for Lieutenant General George S. Patton's U.S. 7th Army and General Bernard L. Montgomery's British 8th Army. Departing the Mediterranean on 3 August, "Herndon" on spent the next nine months escorting troopships across the Atlantic from New York to various British ports as the massive buildup for the invasion of France hit full strike. On D-Day, 6 June 1944, "Herndon" was off Omaha Beach, down front in "Bald-headed Row" ahead of the first assault waves. Despite heavy counter fire from enemy batteries, she bombarded enemy targets ashore.