He was promoted lieutenant by purchase on 12 October 1860, the day Pekin surrendered to the allies,[5] and engaged in the China war at Sinho and at the taking of Tanku and Taku forts.

He was (acting) Deputy Assistant Quartermaster General (QMG) in Bombay from 25 May 1869 to April 1870 when he was sent to Abyssinia on the outbreak of war.

He was in charge of the transport train and was mentioned by Lord Napier in despatches for "zeal, energy and ability".

[11] Another of their first cousins, Dean John Kenny of Kilrush and Ennis, was an active figure in political and social reform in those towns.

His second cousin Fr Matthew J Kenny was one of the first two presidents of the Clare Farmers' Association and a founder member of the Land League.

Ignatius Murphy[12] recounts in his history of Killaloe diocese (p. 225) that Bishop Ryan and his priests met in Ennis to discuss the merits of the various potential candidates and did not endorse Kelly-Kenny.

The paper goes on to quote his resignation letter and also mentions that his (Unionist) cousin Matthew Kenny solicitor of Ennis was his conducting agent.

[13] Cecil Stacpoole Kenny recounts that Major Kelly-Kenny's name was one of the three on the roll that went to the Lord Lieutenant for the High Sheriff of Clare in 1880 but he did not succeed.

[18] At the battle of Paardeberg, Kelly-Kenny had a conservative plan to besiege General Cronje and bombard his Boer force from a safe distance with superior artillery.

[19] Kelly-Kenny was a close friend of King Edward VII who treated him as confidential military advisor.

However, Lord Roberts (the commander in chief) did not share this opinion and viewed Kelly-Kenny as conservative about reform, and the War Office was opposed to his appointment.

He was appointed a Knight Commander of the Order of the Bath (KCB) in the 1902 Coronation Honours list published on 26 June 1902,[22][23] and received the knighthood in a private audience on 2 August, during the King′s convalescence on board HMY Victoria and Albert.

[24] In September 1902, Kelly-Kenny accompanied Lord Roberts and St John Brodrick, Secretary of State for War, on a visit to Germany to attend the German army manoeuvrers as guest of the Emperor Wilhelm.

In 1906,[29] he accompanied Prince Arthur of Connaught to Japan as part of a mission to present the Order of the Garter to the Emperor.

On his return to England he received from King Edward VII the Knight Grand Cross of the Royal Victorian Order (GCVO).

[36] In his Bureau of Military History Witness Statement, Seán Fitzgibbon reports that at a meeting in Dublin on 3 August 1914, the day on which Britain declared war on Germany, Sir Thomas Myles, who the previous weekend had landed a consignment of guns for the Irish Volunteers at Kilcoole, said he had a leader for the Irish Volunteers (who should take over the defence of Ireland and re-create Grattan's Parliament) in the person of Kelly-Kenny.

[39] The executors of his will[40] included his nephews Matthew Devitt, a Jesuit priest, and Thomas O'Gorman, of Cahircalla, to whom he left the bulk of his large estate, with some small bequests to other family members.