On 19 May 1918, U.S.S. ALLEN, in company with U.S.S. PATTERSON, H.M.S. P-62, and several other vessels, encountered what was beleived to be an enemy submarine. After dropping a series of depth charges, ALLEN's commanding officer, Lt. Cmdr. Louis C. Farley, sketched this image to identify the size and location of an oil slick that, he hoped, indicated the destruciton of one of the dreaded U-boats. Postwar exploration of Germna records indicate that no submarine was destroyed on this date.
U.S.S. ALLEN "Report of Action," Destroyer Files, RG 45, United States National Archives and Records Administration, Washington DC.