I whakaritea a Pakenham hei ensign 40th Regiment of Foot i te 23 o Hōngongoi 1803, ka riro hei lieutenant 3 Hui-tanguru 1804, i whakawhiti ki te 95th rifles (i muri mai ko te Rifle Brigade (Prince Consort's Own)) i te Paenga-whāwhā o taua tau, a ka whiwhi i tana kamupene i reira i te 2 o Akuhata 1805. I mahi ia i te haerenga ki Copenhagen me Portugal, i reira i te Pakanga o Roliça
, i whara ohorere ia i Obidos 16-17 Akuhata 1808. "Ko ia tonu tetahi o nga rangatira pai o nga kaipatu i kite ahau", i tuhituhi a Sir Arthur Wellesley, e taunaki ana ia mo te whakatairanga.