After serving in the 4th (Militia) Battalion of the Durham Light Infantry, into which he was commissioned as a lieutenant in December 1882,[8] Kenna, having resigned his commission in August 1884,[9] attended the Royal Military College, Sandhurst and was re-commissioned into the British Army as a lieutenant in the 2nd West India Regiment on 25 August 1886,[10] In 1887 he transferred once again, this time to the 21st Lancers (Empress of India's), and was promoted to captain on 12 June 1895.

[19][20] Following the end of the war that month Kenna returned to the United Kingdom in the RMS Dunottar Castle, which arrived at Southampton in July 1902.

[21] He received the substantive rank of major on 7 September,[22] on his appointment to lead a mounted infantry flying column in Somaliland.

[33] He was killed in action at Suvla, Turkey during the Battle of Gallipoli on 30 August 1915, aged 53 and is buried in Lala Baba Cemetery.

They had one daughter, Kathleen (died 1998) [37] His first cousin, Margaret (née) Larkin (granddaughter of his grandfather Patrick Kenna) married Simon Mangan, HM Lieutenant for County Meath.