▁was ▁placed ▁under ▁the ▁command ▁of ▁Lieutenant ▁Colonel ▁Robert ▁Mar lan , ▁an ▁Australian ▁Staff ▁Corps ▁officer ▁of ▁the ▁P erman ent ▁Military ▁Forces ▁who ▁arrived ▁on ▁promotion ▁from ▁major , ▁having ▁previously ▁served ▁in ▁World ▁War ▁I ▁with ▁the ▁ 2 0 th ▁Battalion . ▁The ▁colours ▁initially ▁chosen ▁for ▁the ▁batt alion ' s ▁Unit ▁Col our ▁P atch ▁( U CP ) ▁were ▁the ▁same ▁as ▁those ▁of ▁the ▁ 1 5 th ▁Battalion , ▁a ▁unit ▁that ▁had ▁served ▁during ▁World ▁War ▁I ▁before ▁being ▁raised ▁as ▁a ▁Milit ia ▁formation ▁in ▁ 1 9 2 1 . ▁These ▁colours ▁were ▁initially ▁pur ple ▁and ▁red ▁in ▁a ▁diam ond ▁shape , ▁but ▁after ▁representations ▁from ▁World ▁War ▁I ▁veter ans ▁the ▁colour ▁patch ▁was ▁changed ▁to ▁brown ▁over ▁dark ▁blue , ▁in ▁a ▁rectangle ▁shape . ▁The ▁patch ▁was ▁placed ▁inside ▁a ▁grey ▁diam ond ▁border ▁added ▁to ▁distinguish ▁the ▁batt alion ▁from ▁its ▁Milit ia ▁counter part ; ▁this ▁would ▁change ▁following ▁the ▁unit ' s ▁invol vement ▁in ▁the ▁fighting ▁at ▁Tob ru k , ▁when ▁it ▁adopted ▁a ▁' T '- sh aped ▁U CP ▁consisting ▁of ▁blue ▁and ▁green . ▁ ▁Following ▁the ▁batt alion ' s ▁establishment , ▁Mar lan ▁set ▁about ▁choosing ▁a ▁cadre ▁of ▁senior ▁commission ed ▁and ▁non - comm ission ed ▁personnel ▁around ▁which ▁to ▁build ▁the ▁batt alion . ▁These ▁personnel ▁included ▁the ▁batt alion ▁second - in - command , ▁the ▁quarter master ▁and ▁adj ut ant