Arthur Nicholas Whistler Colahan (12 August 1884–15 September 1952) was an Irish doctor, British Army officer and songwriterBorn in Enniskillen, County Fermanagh, Ireland his family moved to Galway, where he grew up.Colahan was descended from the Ó hUllacháin family of Lusmagh parish, formerly part of the Síol Anmchadha territory ruled by the Ó Maddan family. The townland of 'Baile Mhac Uallacháin' or Ballymacoolahan (near Banagher) recalls their name. One bearer of the name, Gillafin Mac Coulahan, ruled Síol Anmchadha from 1096 to 1101. John O'Donovan recorded a pedigree of the family covering ten generations from the late 16th century to 1843.Arthur was the eldest child of Professor Nicholas Whistler Colahan (1853-1930) and Elisabeth Quinn of Limerick (b.c.1866). After Arthur was born Ethel (1885–91) Randolph (aka Roland, 1892-1913), Mary (b. 1895), Annie Elzie (b. 1896) and Elizabeth Grace Colohan (born 1897, married Richard Quinn in 1929).His father was the son of Professor Nicholas Colohan (1806-1890) and Sarah Whistler (1814–49). Their children were John (b. 1836), Frances (b. 1843), William H.W., and Nicholas.After completing his secondary education at The 'Bish', he enrolled at University College Dublin in 1900, did an Arts degree and then studied medicine. He transferred to University College Galway and graduated in 1913. He was a member of the college Literary and Debating Society and participated in drama.He began his medical career in the County Infirmary in Galway, and then moved to Holles Street. He joined the Royal Army Medical Corps, and was badly affected by mustard gas in India. After the war he settled in Leicester, where he spent the rest of his career as a neurological specialist.Colahan was also a composer of popular songs. His most famous work is Galway Bay, which popularised by Bing Crosby, was the biggest selling record of all time at one stage. Theories abound as to where the song was written or where it was first heard. Some say it was in the home of Dr Morris at 1 Montpelier Terrace, while others believe it was in The Vicars Croft on Taylor's Hill, from where one could see Galway Bay.Other songs written by Colahan included Maccushla Mine, Asthoreen Bawn, Until God's Day, The Kylemore Pass and The Claddagh Ring.He was a relative of John Fallon Colohan, John Colohan, and Colin Colohan.