FitzGerald was also colonel of the 85th Regiment of Foot (Bucks Volunteers), of the 62nd (Wiltshire) Regiment of Foot and then of the Royal Irish Regiment. He represented County Clare in Parliament on behalf of the Liberal Party from 1852 to 1857. He was advanced to Knight Grand Cross of the Order of the Bath on 19 November 1862 and promoted to field marshal on 29 May 1875. Having retired to France, FitzGerald decided, at an advanced age, to become a convert to the Catholic Church. He died at Tours in France on 24 March 1877; on the orders of Jean Auguste Berthaut, the French Minister of War, the garrison of Tours gave FitzGerald a funeral with the full military honours normally prescribed for a marshal of France. He was buried in St Symphorien cemetery in Tours.