少尉
As Viscount Howick, he served in the British Army, joining the Northumberland Imperial Yeomanry as a Second lieutenant while still at the university. In January 1902 he was appointed a second-lieutenant in the 1st Life Guards. and by 1915 was General Staff Officer 3rd class. He later gained the rank of Major. After service in the Great War Earl Grey was later granted Honorary Colonel of the Northumberland Volunteer Regiment and Nortumberland Fusiliers.