The youngest brother of Philip Gibbs and Cosmo Hamilton, he was educated (1901–1905) at the Collège de St Malo in Brittany. He then took a job with a firm of assayers and refiners of precious metals before being sent at the expense of his brother Cosmo to St John's College, Oxford (1907–9). There he founded the magazine Tuesday Review, in which he published the sketches collected as The Compleat Oxford Man (1911). On graduating, Arthur Gibbs became Cosmo's secretary, taking on various duties including acting in his plays, travelling to America to act in The Blindness of Virtue. In the First World War he served in France, Egypt, and Serbia, winning the Military Cross, and between tours of duty writing up his experiences in Gunfodder (1919). After the war he returned to the USA, married a lawyer and writer, and settled at Lakeville, Massachusetts. He became an American citizen in 1931. His novels, which answered the middlebrow call for fiction to treat ethical dilemmas in tones of moral neatness, includes Cheadle and Son (1911), The Hour of Conflict (1913), The Persistent Lovers (1914), and a series of bestsellers, Soundings (1925), Labels (1926), Harness (1928), and Chances (1930).