MacDonagh is still a young child when his father is executed in 1916 for his part in the Easter Rising. Tragedy strikes again when his mother dies of a heart attack a year afterwards while swimming at Skerries to Lambay Island, County Dublin on July 9, 1917. He and his sister are then cared for by their maternal aunts, in particular Catherine Wilson.
His parents’ families then engage in a series of child custody lawsuits as the MacDonaghs are Roman Catholic and the Giffords are Protestant. In the climate of Ne Temere, the MacDonaghs are successful.
He and his sister Barbara, who later marries actor Liam Redmond, live briefly with their paternal aunt Eleanor Bingham in County Clare before being put into the custody of strangers until their late teens when they are taken in by Jack MacDonagh.
MacDonagh is educated at Belvedere College and University College Dublin (UCD) with contemporaries Cyril Cusack, Denis Devlin, Charles Donnelly, Brian O’Nolan, Niall Sheridan and Mervyn Wall. In 1935 he is called to the Bar and practises on the Western Circuit. In 1941 he is appointed a District Justice in County Mayo. To date, he remains the youngest person appointed as a judge in Ireland. He is Justice for the Dublin Metropolitan Courts at the time of his death.
MacDonagh publishes three volumes of poetry: Veterans and Other Poems (1941), The Hungry Grass (1947) and A Warning to Conquerors (1968). He also edits the Oxford Book of Irish Verse (1958) with Lennox Robinson. He also writes poetic dramas and ballad operas. One play, Happy As Larry, is translated into a number of languages. He has three other plays produced: God’s Gentry (1951), Lady Spider (1959) and Step in the Hollow, a piece of situation comedy nonsense.
MacDonagh also writes short stories. He publishes Twenty Poems with Niall Sheridan, stages the first Irish production of “Murder in the Cathedral” with Liam Redmond, later his brother-in-law, and is a popular broadcaster on Radio Éireann.
MacDonagh is married twice, to Maura Smyth and, following her death after she drowns in a bath whilst having an epileptic seizure, to her sister, Nuala Smyth. He has four children, Iseult and Breifne by Maura and Niall and Barbara by Nuala.
Donagh MacDonagh dies in Dublin on January 1, 1968 and is buried at Deans Grange Cemetery.