Daniel was educated at Blackrock College, Dublin; Royal College of Surgeons, Ireland; and Trinity College, Dublin - qualifying L.R.C.P.I and L.M., L.R.C.S.I. and L.M. in 1889. He took up a commission with the Army Medical Services at the rank of Surgeon Captain on 31st January 1891. He saw active service on the North West Frontier, India from 1897-1898 and in the South African War from 1900-1902, where he was severely wounded and mentioned in dispatches. Further promotions included Brevet Major on the 22nd August 1902; Major on the 31st January 1903; and Lieutenant Colonel on the 5th February 1913. When war was declared, he was appointed Assistant Director of Medical Services [A.D.M.S.] for staff duties on the staff of Surgeon-General Woodhouse. He embarked at Southampton on the 9th August 1914 for France, then arrived in Havre the following day. On 4th September 1914 he was appointed D.A.D.M.S. to the A.D.M.S. of the St Nazaire Base. In July 1915 he proceeded to Gallipoli, acting as A.D.M.S. for the 11th Division. He took part in the landing at Sulva, and was again mentioned in dispatches. After the evacuation of Gallipoli he returned to France, and on 16th May 1916 was promoted to temporary Colonel. He saw active service on the Somme front, where he was a third time mentioned in dispatches, and, in 1917, was awarded the Distinguished Service Order. On the 16th March 1918 he was serving as D.D.M.S., VIII Corps. By May 1918 the VIII Corps had it’s headquarters at Chalons-sur-Marne, where he was in close touch with the administrative medical officers of the French Fourth Army. On 5th June 1918, in order to co-ordinate the work of the British units in French areas, a G.H.Q. (South) was formed, and he became the D.D.M.S. at this G.H.Q. for administering the British medical services. His headquarters were at La Ferte Gaucher. He was replaced by Col C E Pollock a short while after, on 2nd July, when he was appointed A.D.M.S. of the independent Air Force. He was created a Companion Order of St Michael & St George in 1918. After the war, on 6th January 1920, he was placed on half pay. He then retired on 1st February 1920, with the rank of colonel. He died in hospital at Weybridge, Surrey. He was the son of Jeremiah Shanahan of Tralee, co. Kerry, and Joan Shanaham (Nee Davis); and the husband of Henrietta (who died in 1919) - daughter of the late James Young of Kingstown, Dublin.