Under a bareboat charter by the United States Maritime Commission, Agwileon carried civilian technicians and advisors to Sierra Leone for the U.S. Army.

A. G. Smith, General Manager of the Ward Line, agreed to that concession, allowing the Havana to get underway after a two-hour delay.

[3] Several times in 1912, amidst an outbreak of bubonic plague in the Caribbean, Havana operated in violation of Cuban and U.S. quarantine rules.

[4] However, a compromise was worked out by the United States Marine Hospital Service which allowed Havana to depart after a one-day delay.

[7] She was hastily outfitted for trooping duties, and at daybreak on 14 June, USAT Havana, with fellow Army transport ships Saratoga, Tenadores, and Pastores, accompanied by cruisers Seattle, DeKalb, destroyers Wilkes, Terry, Roe, and converted yacht Corsair, set out from Ambrose Light for Brest, France.

[7][8] Corsair was unable to maintain the 15 kn (17 mph; 28 km/h) pace and fell back, being replaced by destroyer Fanning from the second group.

[9] At 22:15 on 22 June, some 850 nmi (980 mi; 1,570 km) from its intended destination of Brest, Havana's group of the convoy was attacked by submarines.

[13] After serving from 24 July – 5 October 1918 as a floating hospital at New York, Comfort joined the Cruiser and Transport Force of the Atlantic Fleet to return wounded men from Europe.

The crew quarters of the ship had also become infested with bedbugs from older German-style hospital bedding and remedies and eradication were performed.

[15] Author and poet William Nelson Morell, in his book of poems related to Navy service during the war, was inspired to write these lines about Comfort: They never billeted a better crew That sailed out of any port Than that which carried the wounded through

The war zone,—on the new "Comfort"The former liner was reacquired by the Ward Line in 1927 and underwent a major refit – removal of one of its stacks and modernization of its interiors – at Todd Shipyard in Seattle, returning to passenger service in the following year.

[19] The captain, Alfred W. Peterson, was found guilty of an "error in judgement in navigation" by using dead reckoning instead of more precise methods of setting course.

[19] In April 1942, the Maritime Commission took control of SS Agwileon under a bareboat charter and used her to transport civilian technicians and advisors to Freetown, Sierra Leone, for the U.S. Army.

[26] The following month, the ship became USAT Agwileon when it was chartered by the Army, and underwent conversion to a troopship at the Atlantic Basin Iron Works in Brooklyn.

With the conversion complete, the new hospital ship left New York in September for Gibraltar and the Mediterranean where she operated locally, calling often at Oran, Palermo, the southern beaches of France, Bizerte, and Naples.

[27] In October, the hospital ship put in at Jacksonville for major repairs, before embarking on a final Mediterranean tour, arriving back in Charleston in April 1945.

With the war in Europe winding down by this time, Shamrock underwent ventilation improvements at the Charleston Navy Yard intended for service in the Pacific.