Lempriere graduated from the Royal Military College, in 1853 where he would be given a commission to Ensign without purchase into the 77th Regiment. In 1853, the Crimean War also broke out and Lempriere along with the 77th Regiment would head to the Crimean Peninsula in 1854. Lempriere would fight with distinction in the Battle of Alma and the Battle of Inkerman. Lempriere was held in good regard by his command for being dependable and was respected by most of his peers despite his size and age. Eventually he would be promoted Captain and command a company.