From October 1917 through the end of World War I, he served in France and was awarded the Silver Star and the Croix de Guerre for his actions during the Belleau Wood Campaign.Over the next 20 years, he served at various stations in the United States and completed tours in Santo Domingo, Nicaragua, and the Panama Canal Zone.Completing shakedown in the Bermuda area in late October, Shannon was ordered to overtake convoy GUS-54 and deliver election ballots before proceeding to Norfolk, Virginia for availability.On 27 January, Shannon, flagship of Mine Division (MinDiv) 7 and a unit of Task Force 51, departed Pearl Harbor for Eniwetok, Saipan, and Iwo Jima.She returned to Iwo Jima on 3 March and resumed duty-night illumination, harassing fire, and call fire- in support of the 4th Marine Division for another five days.Shannon arrived off Kerama Retto, an island group west of Okinawa, on 25 March and covered minesweeping units and underwater demolition teams until that base was secured.From mid-June through the end of July, Shannon accompanied minesweeping units as they continued sweeping operations in the immediate Okinawa area and in the East China Sea.