Kammala jumla mai zuwa: An ba shi izini a matsayin mai bin sawu a 1793, kuma ya zama kyaftin a 1794, ya yi aiki a cikin yakin 1808-9 a cikin Yakin Peninsular, a matsayin Manjo a cikin Rukunin 32nd, kuma ya kasance a yakin da aka yi a
Roliça, Vimiero, da kuma Corunna. Johnson sa'an nan kuma ya yi aiki ta hanyar Walcheren expedition a 1809. A cikin 1810 ya zama laftanan-kolonel a cikin Rundunar Ceylon ta 3.