[8] A preliminary design by General Dynamics envisioned a ship that carried six LCACs, with the ability to turn around (dock, unload or load, then launch) two landing craft simultaneously from the stern.

[8] The ESDs were to host a brigade-size force, sail at 20 knots (37 km/h; 23 mph), and have a maximum range of 9,000 nautical miles (17,000 km; 10,000 mi).

[8] Each ship was to cost US$1.5 billion to build,[8] but cutbacks to defense spending planned for the fiscal year 2011 budget forced the downscaling of the design in mid-2009.

[8] As part of the cost trade-off, the Vehicle Transfer System was scrapped in favor of skin-to-skin mooring of a host ship alongside the ESD, and the LCAC complement was reduced to three.

[9] In March 2013 Chief of Naval Operations Jonathan Greenert showed PowerPoint of the ESD-Expeditionary Mobile Base (ESD-ESB), a proposed variant of the ESD with increased accommodation, a hangar and large flight deck on piers above the semi-submersible deck,[10][11] This was first proposed in January 2012, around the time of the sudden announcement that USS Ponce would be converted as an interim AFSB(I) (ESB).

[12] As of March 2013[update] "a number of variations" of the ESD were being considered;[11] the ESB can fulfill many of the roles of a $2.5 billion "big deck" amphibious ship at a quarter of the price.

[21][22] On 16 January 2014, at the Surface Naval Association's national symposium, the head of NAVSEA's Strategic and Theater Sealift program, Captain Henry Stevens, announced that the MV-22 Osprey tilt-rotor aircraft would be evaluated for potential operations on board the Expeditionary Mobile Base ESD variant.

Additionally, Captain Stevens noted that the F-35B STOVL strike fighter was not then being considered for ESB operations because of exhaust heat from F-35B damaging the flight decks of U.S. Navy amphibious assault ships.

[24] On 19 December 2014, U.S. Navy's Naval Sea Systems Command awarded a US$498M contract to General Dynamics NASSCO for the construction of second ESB variant, the as-yet unnamed T-ESB-4.

[7] After successfully completing this, the vessels sailed to San Diego, where cargo was transferred from Watkins to Mighty Servant 1, then taken ashore by LCACs; slightly submerging the deck of the heavy lift ship allowed the hovercraft to "'fly' aboard".

[6] During these, personnel and a wide range of vehicles, from Humvees to M1 Abrams tanks, were transferred to, then launched from Mighty Servant 3, in conditions up to Sea State 4.

[27] In August 2010, the National Steel and Shipbuilding Company in San Diego was awarded a US$115 million contract to design the Mobile Landing Platform, and build the first ship.

[25] In January 2016, it was announced that T-ESB-4 would be named USNS Hershel "Woody" Williams, after a World War II Marine Corps infantryman who earned a Medal of Honor in the Battle of Iwo Jima.

[42] Effective 4 September 2015, U.S. Secretary of the Navy Ray Mabus officially announced the creation of a new ship designation, "E" for expeditionary support.

The new designation was pursuant to a memorandum sent to Secretary Mabus from Chief of Naval Operations Admiral Jonathan Greenert dated 31 August 2015.

Navy spokesman Lieutenant Tim Pietrack told USNI News: "This re-designation provides combatant commanders greater operational flexibility to employ this platform in accordance with the laws of armed conflict.

Although they were cheap to buy compared to amphibious assault ships and demonstrated seabasing concepts, they are limited to connecting with sealift vessels at wave heights below three feet, and payload, fuel capacity and accommodation space were reduced to cut costs.