One of the first acts of the War Shipping Administration (WSA), established in February 1942, was to address the Navy's pressing need for oilers by requisitioning five tankers in service or under construction for civilian companies.

Three of these were 16.5-knot (30.6 km/h; 19.0 mph) Type T2 "national defense tankers" designed by the Maritime Commission with potential militarization in mind and built by Bethlehem Steel for Socony-Vacuum Oil Co: the Corsicana, Caddo and Calusa.

A month later the WSA requisitioned six more: Socony's Colina and Conastoga, together with four similar ships building at Sun Shipbuilding and Drydock for Keystone Tankships to an enlarged design, later called T2-A: Kalkay, Ellkay, Jorkay and Emkay.

The T2 design had itself been based on two ships built by Bethlehem Steel in 1938–39, Mobilfuel and Mobilube; the T2's principal difference was MarCom's inclusion of more powerful engines to produce the Navy's desired 16.5 knots.

In the meantime MarCom under the State of Emergency had ordered thirteen duplicates of Mobilfuel for the merchant marine; the first of these were nearing completion in late 1942 when the Navy, still very short of oilers, requisitioned the first five starting with Samoset (ex-Mobiloil), renamed USS Chiwawa.