Rubuta ci gaba ga wannan sakin layi - Shelton an ba shi izini a cikin sojojin a matsayin mai ba da izini a cikin 9th (East Norfolk) Regiment of Foot a ranar 21 ga Nuwamba 1805. Shekaru biyu bayan haka ya zama laftana. A cikin 1808 ya ga aikin a yakin Roliça
, Vimiero da kuma Corunna a Portugal. Daga bisani an sake kiran wannan rundunar zuwa Birtaniya. Shelton ya shiga cikin bala'in tafiyar Walcheren na 1809 kafin ya koma yankin Iberian Peninsula a 1812 <unk> 13. A cikin waɗannan shekarun ya halarci yaƙe-yaƙe na Badajoz, Burgos, Salamanca da Vittoria kafin ya ji rauni sosai a lokacin kewaye da San Sebastián, ya rasa hannunsa na dama. An ce ya tsaya a waje da tantinsa ba tare da motsi ba yayin da likitan ya yanke gawar.