The town of Gowran, County Kilkenny, in the early 20th century (© National Library of Ireland).
Colonel Dan Bryan, Director of Irish Military Intelligence (known as G2) 1941–52 (courtesy of Professor Carolle Carter).
Colonel Bryan in later life, taken in the early 1970s (courtesy of Professor Carolle Carter).
Lieutenant General Liam Archer, Director of Irish Military Intelligence (G2) 1932–41 (© Wikimedia Commons).
An Emergency-era Éire sign in Dalkey, Dublin (© Sir Anto/Alamy Stock Photo).
Dr Richard J. Hayes: librarian, G2 agent and codebreaker (courtesy of the Hayes family).
Professor Carolle J. Carter and Dr Hayes in the early 1970s (courtesy of Professor Carolle Carter).
Stephen Hayes (left), one of three wartime IRA chiefs of staff (© Topfoto).
William Warnock, an Irish diplomat who served in Berlin from 1939–43 (© Denver Post via Getty Images).
Con Cremin followed Warnock as Irish chargé d’affaires ad interim in Berlin in 1943 (© Bryan Wharton/Daily Express/Hulton Archive/Getty Images).
Red House, Montpelier Hill, Dublin – headquarters for Irish Military Intelligence circa 1970 (courtesy of Professor Carolle Carter).
Dr Edmund Veesenmayer, a Nazi official who looked after Irish affairs for the SS, 1940–43 (© Ullstein Bild via Getty Images).
Frank Ryan (left), pictured during the Spanish Civil War (© Wikimedia Commons).
Dr Hermann Görtz during his trial at the Old Bailey, London, 4 March 1936 (© Bettman via Getty Images).
A sketch by Dr Görtz of his radio sender, taken from British MI5 surveillance files (© National Archives, London).
MI5 intelligence picture of Wilhelm Preetz, an Abwehr spy sent to Ireland in 1939 (© National Archives, London).
Preetz’s radio set, taken from MI5 files (© National Archives, London).
An Irish Press report of the 1940 Campile bombing (© Irish Newspaper Archive).
Günther Schütz, an image from an MI5 surveillance file (© National Archives, London).
Some of the destruction wrought by the North Strand bombing (© Independent News and Media via Getty Images).
A G2 Officer wearing the parachute of German intelligence spy John Francis O’Reilly (© National Archives, London).
O’Reilly’s radio set, taken from MI5 files (© National Archives, London).
The Shoes on the Danube Bank, a memorial to murdered Hungarian Jews in Budapest (© Koba Samurkasov/Alamy Stock Photo).
Commandant James Power of G2, pictured in the early 1970s at the entrance to the internment camp for German spies at Custume barracks, Athlone (courtesy of Professor Carolle Carter).
Some of the tapes recorded by Prof. Carter during her research trips to Ireland in 1969 and 1970.
Prof. Carter and author Marc Mc Menamin at Stanford University, California, in 2021.