Eclipse was the first of the five, the others being Archer, Independence, Invincible (See Empire Porpoise) and Victorious, entering service as the United States' first electric drive cargo ship making an initial successful voyage from New York in November 1920 to the Dutch East Indies.

[1][2] Reconstructed at the Federal Shipbuilding and Drydock Company, Kearny, New Jersey, to the lines drawn up by the noted naval architect firm of Gibbs & Cox, Eclipse was lengthened by 46'6"; accommodations were installed for 81 tourist-class passengers; and the ship was re-engined to give her a substantial boost in power and speed.

Renamed City of Hamburg, the steamship performed passenger, fast freight, and mail service between the terminal ports of Baltimore, Hampton Roads, Le Havre and Hamburg with the Baltimore Mail Steamship Company from 1938 to 1939, when the United States government refused further subsidies for the firm's international operations.

Shifted to the Mare Island Navy Yard, Vallejo California, soon thereafter, William P. Biddle underwent further alterations there through mid-February.

William P. Biddle took on board 27 officers and 497 enlisted men from the 6th and 2nd Defense Battalions, USMC, while moored at the Long Pier, Destroyer Base, San Diego.

At 1826 on Memorial Day 1941, the transport, flying Commodore Braisted's pennant as ComTransBaseFor, departed San Diego, bound for that duty "beyond the seas."

William P. Biddle passed through the last set of locks – Pedro Miguel – shortly before midnight on the 9th and moored at Cristóbal at 0512 on the 10th to take on fuel.

In response to this request, the President turned to the Navy and discovered that a reinforced infantry regiment, the 6th Marines earmarked for possible expeditionary duty, was already en route from the west coast – a tailor-made Iceland occupation force.

During that time, tensions in the Pacific had reached their peak when a Japanese carrier force attacked Pearl Harbor on 7 December 1941 and pushed the United States over the brink of a rapidly eroding neutrality into war.

William P. Biddle received an augmented antiaircraft battery and new davits to accommodate more up-to-date landing craft before she departed the yard on 15 April.

The task assigned TG 34.9 was a pivotal one, since it was to be launched against the key port of Fedhala, to the northeast of the seaport of Casablanca, on the coast of French Morocco.

William P. Biddle arrived off the Casablanca-Fedhala sector at 0011 on 8 November, heaving-to in the transport area and hoisting out her boats and tank lighters.

The transport continued her unloading evolutions into the following day, a slow process due to lack of boats and lighters, many of which had become stranded on the beaches by the low tide.

Joseph Hewes sank at 2050, and boats from William P. Biddle rescued one officer and 12 men, brought them aboard the transport, and berthed and clothed them.

In keeping with her new designation, the ship entered the Todd-Erie Basin Yard, Brooklyn, New York, to be overhauled and outfitted as an attack transport.

There, she took on board German and Italian prisoners of war for transportation to the United States, departing Oran on the 22nd bound for Newport News, Virginia.

Embarking Marine Corps units at Guantanamo Bay on 28 August, en route, William P. Biddle shifted to Panama on the 30th to pick up Army troops, transited the canal, and arrived at San Diego on 9 September.

On 20 November, the first troops began heading ashore with the 2nd Marine Division landing on Betio Island in the face of stiff resistance.

During the early phase of the landings, at 0550 on the 20th, Japanese shore batteries had opened fire on the transports; five shells had fallen near William P. Biddle, shrapnel wounding one man.

By 1130 on the 23d, Betio was secured; five days later, Major General Julian C. Smith announced that the remaining enemy forces on Tarawa had been wiped out.

Soon thereafter, having delivered her mottle-garbed marines to the beaches of Tarawa, William P. Biddle departed the Gilberts and paused briefly at Pearl Harbor on 2 December on her way to the west coast.

William P. Biddle subsequently embarked marines at San Diego and departed that port on 13 January 1944 bound for Hawaii.

When it became evident that her services would not be required in that operation, William P. Biddle was released from those duties on 3 July and retired to Eniwetok in the Marshalls.

Although two enemy planes had been sighted near the transport area during the frequent air raid alerts, they were out of range and neither the ships nor her boat's guns were fired.

A solitary "Jill" had attacked her formation 100 miles (160 km) east of Leyte Gulf, but gunfire from landing ship vehicle USS Catskill (LSV-1) splashed the intruder before he could do any damage.

With troops from the 1st Battalion, 185th Infantry, 40th Division (Reinforced), USA, embarked, William P. Biddle sailed from the Admiralties on 31 December 1944, bound once more for the Philippines.

William P. Biddle completed debarking her assault waves by 0905 and finished unloading the cargo and troop working parties at 1740.

Her Hawaiian stop was only a brief one for, after 14 months continuous duty outside the continental United States, William P. Biddle was San Francisco bound on 21 March.

Arriving at Leyte on the 28th, William P. Biddle departed that island on 4 August, with casualties and patients – both Army and Navy – embarked.

Struck from the Navy List on 5 June 1946, William P. Biddle was turned over to the Maritime Commission at Lee Hall, Virginia, on 19 July 1946.