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.

His grandfather Charles Seely (1803–1887) was a noted Radical Member of Parliament and philanthropist and was famous for hosting Giuseppe Garibaldi, the Italian revolutionary hero, in London and the Isle of Wight in 1864.

[1] Following the outbreak of the Second Boer War he was commissioned as a captain in the Imperial Yeomanry on 7 February 1900,[6] having succeeded in arranging transport to South Africa for his squadron the same week,[7] with the assistance of his uncle Sir Francis Evans, 1st Baronet, chairman of the Union Castle Line.

[1] He is remembered in South Africa as the commander that placed the 14-year-old Japie Greyling (1890-1954) against a wall in front of a firing squad, threatening to have him executed if he did not provide information about the Boer forces in the area.

[1] He was a strong believer in free trade and was unhappy with the Unionist (Conservative) Party's increasing support for Tariff Reform (protectionism).

[18] Seely was defeated for Abercromby at the January 1910 general election and returned to Parliament for Ilkeston in Derbyshire at a by-election in March 1910, holding that seat until 1922.

In June 1912, apparently on Churchill's suggestion, Seely was promoted to the Cabinet as Secretary of State for War, in succession to Haldane.

[1] Seely supported General Wilson when he gave evidence to the Committee of Imperial Defence (CID) in November 1912 that the presence of the British Expeditionary Force on the continent would have a decisive effect in any future war.

[1] In April 1913 Seely told the House of Commons that the Territorial Force could see off an invasion by 70,000 men and that the General Staff opposed conscription.

Sir John French (Chief of the Imperial General Staff) obtained a partial retraction after Wilson had threatened that he and his two fellow Directors at the War Office would resign in protest at the "lie", but Wilson felt that French's recent promotion to Field Marshal had made him reluctant to clash with Liberal Ministers.

[21] With Irish Home Rule due to become law in 1914, and the Cabinet contemplating some kind of military action against the Ulster Volunteers who wanted no part of it, French and Seely summoned Paget (Commander-in-Chief, Ireland) to the War Office for talks, whilst Seely wrote to the Prime Minister (24 October 1913) about the potential use of General Macready, who had experience of peacekeeping in the South Wales coalfields in 1910, and had been consulted by Birrell (Chief Secretary for Ireland) about the use of troops in the 1912 Belfast riots.

[1] Seely spoke to the assembled Commanders-in-Chief of the Army's six Regional Commands, to remind them of their responsibility to uphold the civil power.

[26] It has been suggested, e.g. by Sir James Fergusson, that the move to deploy troops may have been a "plot" by Churchill and Seely to goad Ulster into a rebellion which could then be put down, although this view is not universally held.

Although the ODNB concurs that Seely was foolish in effectively giving any officers discretion over which orders to obey, he was keen to keep Paget on the government's side and maintain the unity of the Army.

[1] The move to deploy troops resulted in the Curragh incident of 20 March, in which Hubert Gough and many other officers threatened to resign.

Seely had to leave the meeting for an audience with the King, and in his absence the Cabinet agreed a text, stating that the Army Council were satisfied that the incident had been a misunderstanding, and that it was "the duty of all soldiers to obey lawful commands".

[29] Seely, assisted by Viscount Morley, later added two paragraphs, stating that the Crown had the right to use force in Ireland or elsewhere, but had no intention of doing so "to crush political opposition to the policy or principles of the Home Rule Bill".

[29] Gough, on the advice of Maj-Gen Wilson, then insisted on adding another paragraph clarifying that the Army would not be used to enforce Home Rule on Ulster, with which French concurred in writing.

[33] Seely served for near the entirety of the First World War, with few breaks, leaving London on 11 August 1914 to take up a post on Sir John French's staff.

[1] On a liaison mission between the French Fifth Army and Haig's I Corps (31 August 1914 – during the period when Sir John French's retreat had opened up a gap in the Allied line), he claimed to have been almost captured in the fog, but to have bluffed his way past a German cavalry patrol by calling out (in German) that he was a member of the Great General Staff.

Initially acting as an observer, Seely temporarily joined the staff of Archibald Paris, the commander of the British Royal Naval Division, which had been deployed to the city under orders from First Lord Winston Churchill.

When the situation became critical, Seely contacted Lord Kitchener by phone and later received orders for a massive evacuation of the British forces to Ostend.

[1] He was known as "the Luckiest Man in the Army" and was the subject of many apocryphal stories, such as that he recommended his soldier servant for a Victoria Cross for having stood never less than twenty yards behind him during an engagement.

[39][1] During the advance to the Hindenburg Line in spring 1917, Seely, whose brigade was attached to Fourth Army, commandeered infantry from XV Corps to form an ad hoc combat group to capture Équancourt.

Beddington, who had only managed to get to sleep an hour previously, for the first time since the morning of 21 March, on a camp bed in his office, recorded that he "lost (his) temper, cursed him up hill and down dale for daring to wake (him) with such drivel."

I think the noble Lord and all the people who have really met this remarkable man will agree with me on one thing, however much we may disagree about other things—that he is absolutely truthful, sincere, and unselfish".

[53] The Times called him a "Gallant Figure in War and Politics" and Lord Birkenhead wrote, "In fields of great and critical danger he has constantly over a long period of years displayed a cool valour which everybody in the world who knows the facts freely recognizes."

[1] His eldest son and heir, Second Lieutenant Frank Reginald Seely, was killed in action with the Royal Hampshire Regiment at the Battle of Arras on 13 April 1917.

[57] According to the Sir Alfred Munnings Art Museum (Alfred Munnings was a former president of the Royal Academy of Arts and famous horse painter)[58] "Without doubt his most important painting was that of General J. E. B. Seely (later Lord Mottistone) on his charger Warrior which led to his commission to paint the Earl of Athlone, brother of Queen Mary.

At the end of the film Churchill reads a sympathetic post-election note from his old friend Jack Seely: "I feel our world slipping away."