The crown, long a symbol of British dominance in Ireland, represented not just monarchy but imperial control - and in December 1921, opponents of the Anglo-Irish Treaty argued that its terms would forever bind Ireland to that legacy. The newly established Irish Free State would remain part of the British Commonwealth, with only limited sovereignty, leading many to fear this arrangement would never change if the Treaty was accepted. Yet, in just 16 years, Ireland became a republic in all but name. Twelve years later, it officially adopted that name and removed all doubt about its constitutional independence by formally exiting the Commonwealth. Remarkably, this transformation occurred without a single shot fired. This peaceful revolution unfolded through a series of governments from various parties and a remarkable cast of figures: a monarch willing to abdicate for love; a British prime minister who enabled Irish neutrality; and another who tried to coerce Ireland into World War II. What seemed impossible in 1921 was achieved through persistent determination, skilful diplomacy and a fair amount of luck. This is the story of how it happened.

David McCullagh is a journalist, author and presenter with RTÉ, where he has presented the Six One News since 2020. He previously presented the current affairs television programme Prime Time and was political correspondent with RTÉ News. He is the author of a biography of John A. Costello and a two-volume biography of Éamon de Valera.