Baird Smith proceeded to the East India Company's Military Seminary at Addiscombe, from where he obtained his commission in December 1836. He joined the Madras Engineers in 1838. Being transferred to the Bengal Engineers, he served through the second Anglo-Sikh War, and was present at the battles of Hatiiwal, Aliwal and Sobraon. He was then for some years employed on canal work, and when the Indian Mutiny broke out was in charge of Roorkee. He promptly concentrated the Europeans in the workshops, and though the native sappers deserted, his forethought prevented any loss of life.