Here are some of the works written by Declan Joseph O'Gair:
* In Dark Connemara (1922): This novel tells the story of a young man named Michael O'Flaherty who returns to his home in Connemara after fighting in the Irish War of Independence. The novel explores the themes of love, loss, and the struggle for Irish independence.
* The Big Fellow (1931): This novel is a biography of Michael Collins, the leader of the Irish Republican Army during the Irish War of Independence. The novel was a bestseller and was later adapted into a film of the same name.
* The House of the Titans (1934): This novel tells the story of the rise and fall of the Fianna Fáil political party. The novel was a critical and commercial success.
* Famine (1945): This novel tells the story of the Great Famine in Ireland. The novel was a critical and commercial success and was later adapted into a film of the same name.