A Dáil by-election was held in the constituency of Donegal in the Irish Free State on Thursday, 20 November 1924, to fill a vacancy in the 4th Dáil. Donegal was an 8-seat constituency consisting of the administrative county of County Donegal.
Cumann na nGaedheal TD Peter J. Ward resigned on 1 August 1924. The writ of election to fill the vacancy was agreed by the Dáil on 28 October 1924. It was one of five by-elections agreed that day. The Cumann na nGaedheal candidate, Denis McCullough, was a former president of the Irish Republican Brotherhood who had unsuccessfully contested the 1918 general election and the 1921 election.
Result The by-election was held on 20 November 1924. It was the fifth by-election held that week, following the November 1924 Dublin South by-election, the 1924 Mayo North by-election, the 1924 Cork East by-election, and the 1924 Cork Borough by-election. It was won by Denis McCullough.
McCullough took his seat in Dáil Éireann on 26 November, after taking the Oath of Allegiance required under Article 17 of the Constitution of the Irish Free State. McCullough did not contest the June 1927 general election and did not stand for election again.
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