He joined Torpedo Squadron 6 (VT-6) aboard aircraft carrier USS Enterprise on 13 December 1939 and a year later was promoted to lieutenant, junior grade.

In company with the aircraft carrier USS Valley Forge and three other destroyers, Lloyd Thomas visited Sydney, Australia, Hong Kong, and Tsingtao, China.

After Tsingtao, Lloyd Thomas, USS William C. Lawe, and Valley Forge proceeded westward, touching Singapore, Ceylon, and Saudi Arabia, transited the Suez Canal and the Straits of Gibraltar, then steamed north for calls at Bergen, Norway, and Southampton, England.

The formation left England 13 March 1948, spent five days in New York City, and arrived at home port San Diego, Calif. 11 June, having steamed 46,168 nautical miles (85,503 km) during the five-month voyage.

After rigorous operations with the 6th Fleet and calls at Sardinia, Sicily, and Golfe-Juan, France, Lloyd Thomas and her sister destroyers departed Gibraltar on 1 November to escort USS Midway home.

The 1952 voyage included a NATO amphibious landing on the coast of Denmark (Operation "Mainbrace") and port calls in Scotland in England.

On 4 January 1957 the ship departed Newport with Destroyer Division 242 and submarine USS Batfish for South America to acquaint our good neighbors in Colombia, Peru, Ecuador, and Chile with the newest techniques in antisubmarine warfare.

Returning to Newport from Chile 18 March, she conducted local operations until departing 12 August for five months of patrol duty in the Mediterranean and Red Seas.

In 1959, besides hunter-killer training off Norfolk and a summer midshipman cruise to Quebec, Lloyd Thomas again operated with NATO in European waters.

During her duty with the Middle East Force in January and February 1963, the ship visited Ceylon, crossed the equator, and called at the Indian Naval Base in Visakhapatnam.

Then after a brief call at Athens, she spent June and July in the Near East, showing the flag and promoting good will in the nations bordering the Red Sea and Persian Gulf.

On 1 March 1967 Lloyd Thomas, with the rest of Destroyer Squadron 10 (Desron 10), departed Newport for another cruise to the Mediterranean during the Arab–Israeli war.