Thomas Spring Rice, 2nd Baron Monteagle of Brandon was an Anglo-Irish politician and landowner, who helped to found the anti-partition Irish Dominion League and was a key figure in the development of Irish cooperative agriculture.

The Irish Dominion League was an Irish political party and movement in Britain and Ireland which advocated Dominion status for Ireland within the British Empire, and opposed partition of Ireland into separate southern and northern jurisdictions. It attracted modest support from middle-class Dubliners of moderate unionist and nationalist backgrounds, anxious to achieve a compromise in the face of the escalating conflict between the Irish Republican Army and the British. It operated between 1919 and 1921.