During World War II the U.S. Army operated approximately 127,793 pieces of floating equipment. Those included large troop and cargo transport ships that were Army owned hulls, vessels allocated by the War Shipping Administration, bareboat charters and time charters. In addition to the transports the Army fleet included specialized types. Those, included vessels not related to transport such as mine vessels and waterway or port maintenance ships and other service craft. The numbers below give an idea of the scope of that Army maritime operation:
Limiting the number to only the named and numbered vessels, discounting the various simple barges and amphibious assault craft, the remaining number is 14,044 vessels.
This fleet and the Army’s Ports of Embarkation operated throughout the war’s massive logistics in support of the worldwide operations. After the war the Army’s fleet began to resume its peacetime role and even regain the old colors of gray hulls, white deck houses and buff trimming, masts and booms with the red, white and blue stack rings. An example may be seen in the photos of the USAT Fred C. Ainsworth.
Some confusion may exist in the precise definition of "Army ship" as many ships saw Army service during the Second World War that were never (a brief Army time or voyage charter) or only briefly part of the Army's fleet. Army owned vessels of the core fleet are quite clear, even though some of those switched between Army and Navy during the war. Close to those were the ships that were bareboat chartered by the Army, meaning that only the hull itself was chartered and Army was responsible for crewing and all other operational aspects. Others were long term allocations to Army by the War Shipping Administration so that they operated as Army transports and cargo vessels for much of the war. The more confusing ships are those that were short-term or time or voyage chartered ships.
In the South West Pacific Area during the emergency of the Japanese advance throughout Southeast Asia the Dutch East Indies and the Philippines even the chartering arrangements were often vague as ships arriving in Australia were retained by United States Forces in Australia (USFIA) for operations in Australia. Some of these ships, acquired and operating under United States Army Services of Supply, Southwest Pacific Area (USASOS SWPA), achieved some notability in military history in daring voyages to resupply the forces cut off in the Philippines from either Australia or the already collapsing Dutch East Indies. That situation is captured by Masterson on page 324: