▁popular ity ▁of ▁Burn s ' ▁poem . ▁The ▁term ▁came ▁to ▁denote ▁a ▁hat , ▁usually ▁associated ▁with ▁Scottish ▁military ▁reg iments , ▁derived ▁from ▁the ▁old ▁bon net , ▁along ▁with ▁the ▁Gl eng ar ry ▁and ▁the ▁Bal m oral ▁bon net s . ▁The ▁Bal m oral ▁was ▁sometimes ▁simply ▁described ▁as ▁syn onymous ▁with ▁the ▁tam ▁o ' ▁sh anter . ▁ ▁Before ▁the ▁introduction ▁of ▁in exp ensive ▁synth etic ▁d yes ▁in ▁the ▁mid - 1 9 th ▁century , ▁the ▁Scottish ▁kn itted ▁bon net ▁was ▁made ▁only ▁in ▁colours ▁easily ▁available ▁from ▁natural ▁d yes , ▁particularly ▁wo ad ▁or ▁ind igo ▁( h ence ▁" blue ▁bon net "). ▁Since ▁that ▁time ▁the ▁tam ▁o ' ▁sh anter ▁has ▁been ▁produced ▁in ▁a ▁wider ▁range ▁of ▁fab rics , ▁such ▁as ▁ser ge , ▁as ▁single ▁colours , ▁as ▁well ▁as ▁tart an . ▁Women ▁have ▁also ▁adopted ▁a ▁form ▁of ▁this ▁hat , ▁known ▁as ▁a ▁" t am my " ▁or ▁" t am ". ▁ ▁Military ▁use ▁ ▁In ▁the ▁First ▁World ▁War , ▁a ▁k h aki ▁Bal m oral ▁bon net ▁was ▁introduced ▁in ▁ 1 9 1 5 ▁for ▁wear ▁in ▁the ▁tren ches ▁by ▁Scottish ▁inf antry ▁serving ▁on ▁the ▁Western ▁Front . ▁This ▁came ▁to ▁be ▁known ▁as ▁the ▁' bon net , ▁tam ▁o ' ▁sh anter ', ▁later ▁abbre vi ated ▁among ▁military ▁personnel ▁to ▁' To S '. ▁It ▁replaced ▁the ▁Gl