Tuhia he haere tonu mo tenei whitianga - Ko ia te tama matamua a William Smelt (1690 <unk> 14 Mahuru 1755) o Leases i Kirkby Fleetham, MP mo Northallerton i te whare paremata o 1734. Ko te whakatuu tuatahi a Leonard hei kaitohutohu i te Tari Whakataunga i te Pipiri o te tau 1734 i mua i tana noho hei kaiwhawhai cadet i te Royal Artillery hou i te 1 o Hanuere 1739. Kaore tenei i pau i tana wa katoa ka whakaaetia ia ki te haere ki te ruuma whakairo i te Pourewa o Ranana, i reira ia i whakangungu ai i raro i a Clement Lempriere me John Peter Desmaretz ka noho hei tohunga tohunga hoia me te kaihoahoa mahere. I tukuna ia e te Kaiwhakahaere Matua o te Ordnance, te Duke o Montagu, ki a Colonel Thomas Lascelles, kaiarahi miihini i Portsmouth Dockyard, i te Paenga-whawha o te tau 1741 ana e rua marama noa iho ka tūtohu a Lascelles kia whakawhiwhia e Montagu ki a ia te taumata o te miihini mahi. I te 13 o Akuhata 1741 i whakawhiwhia ki a ia he pou i te Pourewa o Ranana e te Tiamana John Armstrong, Kaiwhakamatau-Tianara o te Ordnance me te Kaiwhakahaere Matua Royal. I tata ki te kotahi tau te roa o tenei pou i mua i tana tohatoha ki te kaha o Ingarangi i Flanders i te 19 o Pipiri o te tau e whai ake nei, ka uru ki te tereina patu i reira ka whawhai i Dettingen
me Fontenoy. I whiwhi hoki ia i te whakatairanga ki te Engineer Extraordinary i te 8 o Poutu-te-rangi 1744, ka peke atu ki te taumata takawaenga o te kaihauturu. I te tau 1745 i tangohia ia e Kapene Thomas, Royal Engineers, he tangata no te Duke o Cumberland, a ka whakatika ngatahi raua ka whakawhānui i nga whakapae o Vilvorden Castle <unk> i whakaputaina e raua he mahere mo te kaupapa hou kei te Whare Pukapuka o Ingarangi inaianei.