SM U-4
... that SM U-4, commissioned in 1909, was the longest serving U-boat of the Austro-Hungarian Navy?
... that <b id="mwCME"><a about="#mwt22" data-mw='{"parts":[{"template":{"target":{"wt":"warship","href":"./Template:Warship"},"params":{"1":{"wt":"SM"},"2":{"wt":"U-4"},"3":{"wt":"Austria-Hungary"},"4":{"wt":"6"}},"i":0}}]}' href="./SM_U-4_(Austria-Hungary)" id="mwCMI" rel="mw:WikiLink" title="SM U-4 (Austria-Hungary)" typeof="mw:Transclusion">SM<span typeof="mw:Entity"> </span><i>U-4</i></a></b>, <a href="./Ship_commissioning" id="mwCMM" rel="mw:WikiLink" title="Ship commissioning">commissioned</a> in 1909, was the longest serving <a href="./U-boat" id="mwCMQ" rel="mw:WikiLink" title="U-boat">U-boat</a> of the <a href="./Austro-Hungarian_Navy" id="mwCMU" rel="mw:WikiLink" title="Austro-Hungarian Navy">Austro-Hungarian Navy</a>?