Rudolph Lambart , 10th Earl of Cavan Field Marshal Frederick Rudolph Lambart , 10th Earl of Cavan , KP , GCB , GCMG , GCVO , GBE , DL ( 16 October 1865 – 28 August 1946 ) was a British Army officer and Chief of the Imperial General Staff . He served in the Second Boer War , led XIV Corps during World War I and later advised the Government on the implementation of the Geddes report , which advocated a large reduction in defence expenditure , and consequentially he officiated over a major reduction in the size of the British Army . Army career . Born the son of Frederick Lambart , 9th Earl of Cavan and Mary Sneade Lambart ( née Olive ) and educated at Eton College , Christ Church , Oxford and the Royal Military College , Sandhurst , Lambart was commissioned into the Grenadier Guards on 29 August 1885 . He gained the courtesy title of Viscount Kilcoursie in 1887 when his father succeeded to the Earldom and was appointed Aide - de - Camp to the Governor General of Canada in 1891 . Having been promoted to captain on 16 October 1897 , he saw action as a company commander in the Second Boer War at the Battle of Biddulphsberg in May 1900 and , having succeeded to his father ' s titles on 14 July 1900 , took part in operations against the Boers in 1901 and was mentioned in despatches . After promotion to major on 28 October 1902 , he became second - in - command of 2nd Battalion Grenadier Guards in July 1905 . He was promoted again to lieutenant colonel and appointed Commanding Officer of 2nd Battalion Grenadier Guards on 14 February 1908 . Appointed LVO on 29 June 1910 and promoted to colonel on 4 October 1911 , he retired from the British Army on 8 November 1913 and became Master of Foxhounds for the Hertfordshire Hunt . At that time he lived at Wheathampstead House in Wheathampstead . He was recalled at the start of World War I and was appointed commander of 4th Guards Brigade on 11 August 1914 and went on to lead the Brigade at the First Battle of Ypres in October 1914 . Appointed CB on 18 February 1915 , he also led the Brigade at the Battle of Festubert in May 1915 . Cavan was promoted to major - general and given command of the 50th ( Northumbrian ) Division on 29 June 1915 ; a mere two months later he was appointed the first commander of the Guards Division and , having been appointed Commander of the French Legion of Honour on 10 September 1915 , he led his Division at the Battle of Loos later that month . He was elected a representative peer from Ireland on 24 September 1915 and as such was one of the last to be so elected before the creation of the Irish Free State . In his role as Commander of the Guards Division he informed Major Winston Churchill of the latter ' s attachment to the 2nd Battalion of the Grenadiers in November 1915 . The following January 1916 , Cavan was placed at the head of XIV Corps and took part in the Battle of the Somme that Summer . He was made a Grand Officer of the Belgian Order of the Crown on 2 November 1916 and appointed a Knight of the Order of St . Patrick on 18 November 1916 . Promoted to Lieutenant General on 1 January 1917 , he led his Corps at the Battle of Passchendaele in Summer 1917 . He was awarded the rank of Grand Officer of the Legion of Honour on 25 September 1917 and was redeployed with his Corps to Italy on October 1917 . Advanced to KCB on 1 January 1918 , Cavan was appointed Commander - in - Chief of British forces on the Italian Front on 10 March 1918 . It was in this capacity that Cavan led the Tenth Army which struck a decisive blow at the Battle of Vittorio Veneto , the action that sounded the final death knell of the Austro - Hungarian Army towards the close of the war . Following the end of the War the King of Italy awarded him the Cross of War and made him a Commander , and subsequently a Grand Officer , of the Military Order of Savoy as well as appointing him a Grand Officer of the Order of St Maurice and St Lazarus . Cavan was also appointed GCMG for his contribution to operations in Italy , awarded the American Distinguished Service Medal and appointed to the Chinese Order of Wen - Hu ( 1st Class ) . His first appointment after the War was when he became Lieutenant of the Tower of London on 22 March 1920 . Appointed ADC to the King on 1 October 1920 , he became General Officer Commanding at Aldershot Command on 2 November 1920 before being promoted to full general on 2 November 1921 . He was appointed Chief of the Imperial General Staff on 19 February 1922 . He may have been chosen as a steady man , the antithesis of his predecessor Henry Wilson , whose relations with the government had deteriorated , and who was in Wilson ’ s view more likely to agree to withdraw troops from Egypt and India . As CIGS Cavan advised the Government on the implementation of the Geddes report , which advocated a large reduction in defence expenditure , and consequentially he officiated over a major reduction in the size of the British Army . Advanced to GCB in the New Year Honours 1926 , he retired on 19 February 1926 . He was also Colonel of the Irish Guards from 23 May 1925 and Colonel of the Bedfordshire and Hertfordshire Regiment from 10 December 1928 . In retirement he became Chairman of the National Playing Fields Association and Deputy Lieutenant of Hertfordshire . Appointed GBE on 8 July 1927 , he became Captain of the Honourable Corps of Gentlemen - at - Arms on 23 July 1929 and was promoted to field marshal on 31 October 1932 . He also took part in the procession for the funeral of King George V in January 1936 and commanded the troops at the procession for the coronation of King George VI on 12 May 1937 . During World War II he served as Commanding Officer of the Hertfordshire Local Defence Volunteers . He died at the London Clinic in Devonshire Place in London on 28 August 1946 . He was buried in the family plot at the churchyard in Ayot St Lawrence , where a seven - feet tall red granite cross is his headstone . His is the churchyard ' s only burial registered as Commonwealth war grave . Marriage and family . He married on 1 August 1893 to Caroline Inez Crawley ( 1870 – 1920 ) , daughter of George Baden Crawley and Eliza Inez Hulbert , at Digswell Church in Digswell , Hertfordshire . She predeceased her husband ; they had no children . He married , secondly , on 27 November 1922 to Lady Hester Joan Byng , daughter of Reverend Francis Edmund Cecil Byng , 5th Earl of Strafford and Emily Georgina Kerr , at St . Mark ' s Church in North Audley Street , Mayfair , London . Joan , the Countess of Cavan , would , in 1927 , be knighted as a Dame Commander of the Order of the British Empire . The couple had two daughters : Because he had no son , he was succeeded in his peerage by his brother , Horace .