After her completion in 1918, the Shipping Board transferred her to the U.S. Navy at Portland on 30 July 1918 for use during World War I. Assigning her the naval registry identification number 3300, the Navy commissioned her at Portland on 30 July 1918 as USS Western Light (ID-3300).

[2][3] Western Light departed Portland in August 1918 and steamed to Arica, Chile, where she loaded a full cargo of nitrates.

On 17 September 1918, she got underway, proceeded through the Panama Canal and arrived on 7 October 1918 at Philadelphia, Pennsylvania.

[5] Carrying flour and lard, Western Light departed New York in January 1919 and steamed to Falmouth, England, where she discharged her cargo.

[6] During her three U.S. Navy transatlantic voyages, Western Light delivered a total of 17,540 tons of hay, oats, flour, and lard, as well as various U.S. Army supplies.