As part of this program, EFC placed orders with nation's shipyards for a large number of vessels of standard designs.

Mopang was part of the second optional order for 68 additional vessels placed by USSB with Submarine Boat Corp. on 16 November 1917.

[1][2] On this occasion the Society chartered steamer Chester W. Chapin and nearly 250 members and their families attended the launching ceremony.

[3] Following delivery and acceptance by the USSB, Mopang was immediately allocated to Lykes Brothers to serve on their Gulf to Europe and United Kingdom routes.

[7][8] After loading her cargo consisting of several hundred thousands feet of planks, ash, pine, gum tree and mahogany lumber and staves in addition to other general merchandise, the freighter departed New Orleans on February 10 bound for London.

[10] Prior to her arrival, on March 11, she suffered broken steering gear which caused the vessel to stay in port until repairs were finalized.

Upon delivery Mopang was put on this route, and after several delays cleared from New York on December 28, carrying among other cargo approximately 700 tons of food aid destined for the Republic of Armenia.

[23] Upon her arrival Mopang was chosen by the American Committee for Relief in the Near East to carry large quantities of food supplies to famine victims in Armenia.

The cargo was collected and loaded over the two months period and consisted of nearly 2,000 tons of foodstuffs in addition to large quantity of flour.

[25] The freighter eventually sailed out from New York on May 25 bound for Constantinople, where she were to unload the bulk of her cargo, and then continuing on to Burgas and Constanța.

Mopang then proceeded to enter the Burgas Bay, but at approximately 05:30 when she was 1.7 nmi (3.1 km) off Megalo Nisi light, she hit an old World War I-era naval mine.

In July all crew members with the exception of the captain sailed back to the United States on board steamer SS Magnahelias.

The captain stayed behind temporarily in an attempt to recover the ship's safe in case salvage operations would be ordered, however, USSB decided not to pursue them.