[1] She spent most of the war based at Gibraltar, escorting and protecting Allied ships in the Mediterranean and along the Atlantic Ocean coast of Europe.

Lydonia II was constructed for William A. Lydon, commodore of the Chicago Yacht Club, by Pusey and Jones in Wilmington, Delaware as Hull #348 under contract #1205 received 20 February 1911 and was more than 250 gross tons larger than the first yacht bearing the name, Lydonia I, completed for Lydon just two years earlier.

[1][2][3][note 1] Named in honor of Lydon's family Lydonia II was designed by William A. Gardner with construction started in early April 1911.

Various service spaces were located forward of the engine room casing that had a large observation window fitted for viewing the machinery from the starboard deck passage.

A vertical type donkey boiler, 4 ft 9 in (1.4 m) in diameter, was located in the fire room convenient to the coal bunkers.

[6] After repairs and target practice off Bermuda, Lydonia departed the Caribbean in mid-November 1917 and arrived at Horta in the Azores on 7 December 1917.

[6] Lydonia spent the early months of 1918 protecting Allied Mediterranean supply convoys from attacks by Imperial German Navy submarines (U-boats).

Lydonia joined the British Royal Navy destroyer HMS Basilisk in counterattacking UB-70 beginning at 17:35, with the two ships making coordinated depth charge attacks.

Heavy seas prevented an immediate assessment of possible damage to UB-70, but later evaluations credited Lydonia and Basilisk with sinking the submarine.

After the conclusion of the war on 11 November 1918, she called at the Azores and Caribbean ports on her way back to the United States, where she arrived at Hampton Roads, Virginia, on 6 February 1919.

[6] The U.S. Navy decommissioned Lydonia at Norfolk, Virginia, 7 August 1919 and transferred her to the United States Coast and Geodetic Survey the same day.

On 7 August 1921, she assisted in helping survivors and searching for bodies in the wreck of the steamboat SS Alaska on Blunt's Reef off the coast of northern California.

In May 1927, she and the survey ship USC&GS Hydrographer were sent to Memphis, Tennessee, to help victims of the great Mississippi River flood of that year.

[8] On 23 August 1933, Lydonia was with the Coast and Geodetic Survey survey ships USC&GS Oceanographer and USC&GS Gilbert at Norfolk, Virginia, when the 1933 Chesapeake–Potomac hurricane struck; the three ships handled considerable radio traffic for the Norfolk area, including U.S. Navy traffic, during the storm.

Lydonia′s commanding officer in 1941, Lieutenant Commander H. Arnold Karo, went on to serve as director of the Coast and Geodetic Survey from 1955 to 1965 and as deputy administrator of the Environmental Science Services Administration from 1965 to 1967 and became the first Coast and Geodetic Survey Corps officer to reach the rank of vice admiral.