as ian ▁Championships ▁in ▁ 1 9 1 1 , ▁as ▁a ▁ 1 7 - year - old . ▁At ▁the ▁ 1 9 1 4 ▁Austral as ian ▁Championships ▁he ▁reached ▁the ▁semi - final s ▁in ▁the ▁singles ▁competition , ▁which ▁remained ▁his ▁best ▁performance . ▁His ▁loss ▁in ▁the ▁semi - final s ▁was ▁to ▁event ual ▁champion ▁Arthur ▁O ' H ara ▁Wood , ▁a ▁fellow ▁al umn us ▁from ▁his ▁resident ial ▁college , ▁in ▁four ▁sets . ▁ ▁Due ▁to ▁his ▁German ▁her itage , ▁W ert heim ▁was ▁nick named ▁" S os " ▁or ▁" S oss ", ▁for ▁sa usage . ▁He ▁later ▁served ▁in ▁Germany ▁as ▁a ▁member ▁of ▁the ▁Australian ▁Imperial ▁Force ▁during ▁World ▁War ▁I . ▁After ▁en list ing ▁in ▁ 1 9 1 5 , ▁W ert heim ▁went ▁to ▁Gal lip oli ▁with ▁the ▁ 2 3 rd ▁Battalion ▁but ▁only ▁saw ▁the ▁final ▁month ▁of ▁the ▁campaign . ▁He ▁transferred ▁after ▁that ▁to ▁the ▁ 2 nd ▁P ione er ▁Battalion ▁in ▁March ▁ 1 9 1 6 ▁and ▁fought ▁in ▁Poz ières ▁from ▁July ▁to ▁August ▁and ▁then ▁in ▁Fl ers . ▁In ▁ 1 9 1 7 ▁he ▁was ▁second ed ▁to ▁the ▁Int elligence ▁Corps ▁and ▁is ▁cred ited ▁with ▁obtain ing ▁vital ▁information ▁from ▁a ▁German ▁prisoner ▁to ▁a vert ▁a ▁planned ▁counter - att ack . ▁He ▁was ▁mentioned ▁in ▁des patch es ▁three ▁times ▁during ▁the ▁war , ▁included ▁those