Major General John Edward Bernard Seely, 1st Baron Mottistone CB, CMG, DSO, TD, PC, JP, DL (31 May 1868 – 7 November 1947) was a British Army general and politician. He was a Conservative Member of Parliament (MP) from 1900 to 1904 and a Liberal MP from 1904 to 1922 and from 1923 to 1924. He was Secretary of State for War for the two years prior to the First World War, before being forced to resign as a result of the Curragh Incident. As General Jack Seely, he led one of the last great cavalry charges in history at the Battle of Moreuil Wood on his war horse Warrior in March 1918. Seely was a great friend of Winston Churchill and the only former cabinet minister to go to the front in 1914 and still be there four years later.
Seely was a member of a family of politicians, industrialists and significant landowners. His father Sir Charles Seely, 1st Baronet, brother Sir Charles Seely, 2nd Baronet, nephew and grandfather were all Members of Parliament. His grandfather Charles Seely (1803–1887) was a noted philanthropist and famous for hosting Giuseppe Garibaldi, the Italian revolutionary hero, in London and the Isle of Wight in 1864. Seely's nephew Sir Hugh Seely, 3rd Baronet and 1st Baron Sherwood, was Under-Secretary of State for Air during the Second World War. His eldest son from his second marriage, David Peter Seely, 4th Baron Mottistone, was the last Governor of the Isle of Wight; he was baptised with Winston Churchill and the then Duke of Cornwall (subsequently Edward VIII, and then later HRH Duke of Windsor) as his godparents.