Operation Caesar
... that the 1945 loss of German U-boat U-864 during Operation Caesar, a secret mission to deliver technology to Japan, is the only known incident of one submerged submarine sinking another?
... that the 1945 loss of <a href="./Nazi_Germany" id="mwBTw" rel="mw:WikiLink" title="Nazi Germany">German</a> <a href="./U-boat" id="mwBT0" rel="mw:WikiLink" title="U-boat">U-boat</a> <a class="mw-redirect" href="./Unterseeboot_864" id="mwBT4" rel="mw:WikiLink" title="Unterseeboot 864"><i id="mwBT8">U-864</i></a> during <b id="mwBUA"><a href="./Operation_Caesar" id="mwBUE" rel="mw:WikiLink" title="Operation Caesar">Operation Caesar</a></b>, a secret mission to deliver technology to <a href="./Empire_of_Japan" id="mwBUI" rel="mw:WikiLink" title="Empire of Japan">Japan</a>, is the only known incident of one submerged submarine sinking another?