West Pocasset was a steam cargo ship built in 1919 by Northwest Steel Company of Portland for the United States Shipping Board as part of the wartime shipbuilding program of the Emergency Fleet Corporation (EFC) to restore the nation's Merchant Marine. The freighter was operated sparingly on the United States to Europe routes during the first two years of her career before being laid up. The ship was briefly reactivated in 1929 but was again laid up next year and remained idle for the next ten years. In January 1941 the freighter was sold together with four other vessels to the United States Line and was put under operation by its fully owned Panama-registered subsidiary to carry war matériel and supplies between Canada and United Kingdom and renamed Chepo. In early January 1942 while on o