Irish diplomats spied for the United States during the course of the war. Irish diplomats in Europe carried messages and supplied information to the OSS - the predecessor of the CIA - with the full knowledge and consent of de Valera. Behind the Green Curtain is a comprehensive account of Irish neutrality, focusing strongly on the American - and to a lesser extent the Canadian - connection. It confirms beyond any doubt that Ireland made a positive and partisan contribution to the allied war effort. Neutrality has become a shibboleth of modern Irish politics. Behind the Green Curtain explodes the myth behind that shibboleth in the most decisive way.

From the reviews:

Excellent and probably definitive account of Irish neutrality during the Second World War. Kevin Myers, Irish Independent

With his brilliantly researched book, Dwyer confirms his status as a walking encyclopaedia of Irish history...as a work of scholarship, Behind the Green Curtain is nothing less than superb. Andrew Lynch, Sunday Business Post