Eliott served as ADC to King George II between 1756 and 1759 during which time he was raised to Colonel. Appointed Brigadier for the 1758 expedition to France, where he was placed in command of the Brigade of Light Cavalry, He was tasked to raise and was appointed colonel of the 1st Light Horse (later 15th Light Dragoons, then 15th Hussars). Eliott distinguished himself in the German campaign, particularly during the Battle of Minden in 1759 when he was promoted to Major-General and the 1760 Battle of Emsdorf.