For Ryan’s family background see Aodh Ó Canainn, ‘Oral history: Eilís Ryan in her own words’, Saothar, 21 (1996), pp 129–46. The records of the departments of Justice, the Taoiseach and External Affairs in the National Archives of Ireland provide a wealth of detail on Ryan. Rosamond Jacob’s personal papers in the National Library are a valuable source for Ryan and the broader radical milieu of inter-war Dublin. For IRA activism, see the collection of interviews in Uinseann MacEoin’s The IRA in the Twilight Years, 1923–1948 (Dublin, 1997). Ryan’s political writings can be found in numerous inter-war radical political newspapers, particularly those he edited including An Phoblacht, Republican Congress, Irish People and the Irish Democrat.
Primary sources for Ryan in Spain include the Imperial War Museum’s Spanish Civil War oral history collection and the records of the International Brigade Association in the Marx Memorial Library (both in London). Sources shedding light on Ryan’s imprisonment in Spain and his activities in Nazi Germany can be found in the National Archives’ D/FA A20 collection, the (Irish) Military Archives’ G2 collection and MI5’s KV series in the National Archives (UK).
Seán Cronin’s Frank Ryan: The Search for the Republic (Dublin, 1980) is a well detailed but essentially uncritical biography. A more critical concise biography, Frank Ryan, written by Fearghal McGarry was published by Dundalgan Press as part of the Historical Association of Ireland’s Life and Times series in 2002. A revised edition of this book, which formed a key source for Des Bell’s film screenplay, was published by UCD Press in 2010. A third biography of Frank Ryan, written by Adrian Hoar, In Green and Red: The Lives of Frank Ryan, was published by Brandon in 2004.
Brian Hanley’s excellent study, The IRA, 1926–36 (Dublin, 2002), sheds much new light on the inter-war IRA. Previous surveys of the IRA by Tim Pat Coogan and J. Bowyer Bell have been superseded by Richard English’s more critical Armed Struggle: A History of the IRA (London, 2003). Tom Garvin’s Nationalist Revolutionaries in Ireland, 1858–1928 (Oxford, 1987) reconstructs a republican mentality of which Ryan can be seen as an archetypal example. Brian Murphy’s Patrick Pearse and the Lost Republican Ideal (Dublin, 1990) provides an insightful, if partisan, analysis of the legitimist republican tradition.
More critical reflections on the ideological inconsistencies which beset inter-war left republicanism are provided by Richard English’s Radicals and the Republic: Socialist Republicans in the Irish Free State, 1925–1937 (Oxford, 1994). Donal Ó Drisceoil’s biography, Peadar O’Donnell (Cork, 2001), offers a sympathetic assessment of Ryan’s political mentor. Irish links with international communism are explored in Emmet O’Connor’s Reds and the Green: Ireland, Russia and the Communist Internationals, 1919–43 (Dublin, 2004) and Barry McLoughlin’s Left to the Wolves: Irish Victims of Stalinist Terror (Dublin, 2007). Fearghal McGarry’s Eoin O’Duffy: A Self-Made Hero (Oxford, 2007) assesses the life of Frank Ryan’s political nemesis. For the broader diplomatic and security context, see Dermot Keogh’s Ireland and Europe, 1919–1948 (Dublin, 1988) and Eunan O’Halpin’s Defending Ireland: The Irish State and its Enemies since 1922 (Oxford, 1999).
Irish involvement in Spain is detailed in Michael O’Riordan’s Connolly Column (Dublin 1979), Bill Alexander’s British Volunteers for Liberty (London, 1982) and, more critically, James Hopkins’s thoughtful Into the Heart of the Fire: The British in the Spanish Civil War (Stanford, 1998). Robert A. Stradling’s The Irish and the Spanish Civil War, 1936–1939 (Manchester, 1999) and Fearghal McGarry’s Irish Politics and the Spanish Civil War (Cork, 1999) examine the Irish in Spain and the impact of that conflict on Irish politics. More new information on the British Battalion, the unit in which Frank Ryan and most of the Irish volunteers in Spain fought in, is contained in Richard Baxell’s British Volunteers in the Spanish Civil War: The British Battalion in the International Brigades, 1936–1939 (London, 2004).
Important new accounts of the Irish in Germany include David O’Donoghue’s Hitler’s Irish Voices: The Story of German Radio’s Wartime Irish Service (Belfast, 1998) and his The Devil’s Deal: The IRA, Nazi Germany and the Double Life of Jim O’Donovan (Dublin, 2010). The Wartime Broadcasts of Francis Stuart, 1942–1944, edited by Brendan Barrington (Dublin, 2000), provides a revealing insight into another Irish republican whose activities in wartime Berlin were both overlooked and distorted. The IRA’s murky contacts with Nazi Germany have been comprehensively detailed in Mark Hull’s German Espionage in Ireland, 1939–1945 (Dublin, 2003). The efforts of British intelligence agencies to cope with the wartime threat posed by both the IRA and the neutral Irish State are authoritatively assessed in Spying on Ireland: British Intelligence and Irish Neutrality during the Second World War by Eunan O’Halpin (Oxford, 2008).