O’Donovan moves to London but, failing to find work as a priest, he leaves the Catholic priesthood in May 1908. He becomes a subwarden at Toynbee Hall in the East End in March 1910. In October that year, he marries Florence Emily Beryl Verschoyle (1886–1968), the daughter of an Irish Protestant colonel fifteen years his junior. They have three children, two daughters and a son.
In 1913, O’Donovan publishes his first and best known novel, Father Ralph, which draws in large part on his own life. Around this time he changes his first name from Jeremiah to Gerald. Another novel titled Waiting is published in 1914. He joins the war effort in 1915, and rises to become head of the Italian section at the Ministry of Information in 1918. There he meets his secretary and future lover, English novelistRose Macaulay.
O’Donovan publishes a few more novels after the war: How They Did It (1920), Conquest (1920), Vocations (1921), and The Holy Tree (1922). The clandestine affair with Macaulay continues for nearly two decades. In 1939, the pair are on holiday in the Lake District when they meet with a motoring accident, which damages O’Donovan’s health. He dies of cancer in Albury, Surrey three years later, on July 26, 1942. His letters to Macaulay had been destroyed the previous year when her flat in Central London was bombed during the Blitz.
In her novel The Towers of Trebizond, Macaulay features a woman character (Laurie) torn between her attraction to Christianity and her adulterous love for a married man. This is considered to reflect the author’s relationship with O’Donovan.
When the unit is originally mustered out of service, the 90-day enlistment terms having expired, Nugent accepts a commission as a captain in the regular army. He is immediately assigned to the 13th Infantry Regiment whose commanding officer, Colonel William Tecumseh Sherman, personally requests. Taking a leave of absence to return to New York, he assists Thomas Francis Meagher in organizing the Irish Brigade. The newly reformed 69th Infantry Regiment is the first unit assigned to the Irish Brigade and, with Nugent as its colonel, he leads the “Fighting 69th” at the Battles of Fair Oaks, Gaines’s Mill, Savage’s Station, White Oak Swamp, Glendale and Malvern Hill.
Nugent is shot in the stomach at the Battle of Fredericksburg and is eventually forced to resign his command. He is appointed acting assistant provost marshal for the southern district of New York, which includes New York City and Long Island, by the United States War Department. An Irishman and Democrat, his appointment is thought to assure the Irish American population that conscription efforts would be carried out fairly. The Irish American, a popular Irish language newspaper, writes that the selection is a “wise and deservedly popular one.” He encounters resistance from city officials wanting to remain uninvolved, however by mid-June reports to his superior officer and provost marshal general Colonel James Barnet Fry that conscription efforts are “nearing completion without serious incident.”
Understanding the seriousness of the situation, Nugent attempts to keep the draft selections quiet and in isolated parts of the city. In Manhattan however, lotteries are placed in the heart of Irish tenement and shanty neighborhoods where the draft is most opposed.
In the ensuing New York City draft riots, Nugent takes command of troops and attempts to defend the city against the rioters. Despite issuing the cancellation of the draft, the riots continue for almost a week. His home on West 86th Street is looted and burned by the rioters during that time, his wife and children barely escaping from their home. Upon breaking into his house, furniture is destroyed and paintings of Nugent and Meagher are slashed, although a painting of Brigadier General Michael Corcoran is reportedly left untouched.
Nugent is brevetted Brigadier General for distinguished leadership of the 69th Regiment on March 13, 1865. The veterans of the Irish Brigade are honorably discharged and mustered out three months later. Nugent remains in the regular U.S. Army for the next twenty years, a formidable “Indian fighter” during the American Indian Wars with the 13th and 24th Infantry Regiments. In 1879, he retires at the rank of major and resides in New York where he is involved in the Grand Army of the Republic, the War Veterans’ Association of the 7th Regiment and an honorary member of The Old Guard.
Nugent becomes ill in his old age, complications arising from his wounds suffered at Fredericksburg, and remains bedridden for two months before his death at his McDonough Street home in Brooklyn on June 20, 1901. In accordance with his last wishes, he is buried at Cypress Hills National Cemetery.