第一次エチオピア戦争
Slade was commissioned into the Royal Artillery in 1861. After taking part in the Bazaar Valley Expedition in 1878, he commanded a battery at the Battle of Maiwand in July 1880 during the Second Anglo-Afghan War. He served as a staff officer during the First Boer War and then became military attaché in Rome in 1887. He also served as a staff officer assisting General Antonio Baldissera during the First Italo-Ethiopian War before becoming General Officer Commanding the British Troops in Egypt in 1903.