In 1799 Kempt accompanied Sir Ralph Abercromby to the Netherlands, and later to Egypt as an aide-de-camp. After Abercromby's death, Kempt remained on his successor's staff until the end of the campaign in Egypt. In April 1803 he joined the staff of Sir David Dundas, but next month returned to regimental duty, and a little later received a lieutenant colonelcy in the 81st Foot. With his new regiment he went, under Craig, to the Mediterranean theatre of operations, and at the Battle of Maida on 4 July 1806, he led the light infantry brigade which bore the heaviest share of the battle.