sentences:  "U-864" was carrying a cargo of 65 tonnes of mercury as well as Junkers Jumo 004B jet engine parts (used in the Messerschmitt Me 262) to Japan, a mission code-named Operation Caesar.On 6 February 1945, "U-864" passed through the Fedje area without being detected, but on 9 February "Venturer" heard "U-864"s engine noise.Launders had decided not to use ASDIC since it would betray his position and spotted the U-boat's periscope as her captain looked for his escort.