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Dr. Sen Duffy

Professor Seán Duffy

Professor of Medieval Irish and Insular History

Research Interests

Seán Duffy specializes in the history of medieval Ireland and, in particular, three aspects: first, the political history of Ireland from the Viking Age to the Bruce Invasion; second, Irish relations with England, Scotland, and Wales in the same period; and third, the history and archaeology of medieval Dublin.

Select Publications

  • Medieval Dublin: Proceedings of the Friends of medieval Dublin Symposium (Editor. Dublin: Four Courts, 1999-). [sixteen vols have appeared to date]
  • The Geraldines and medieval Ireland: The Making of a Myth. Trinity Medieval Ireland Series I (Editor, with Peter Crooks. Dublin: Four Courts Press, 2016), 445pp
  • A New History of the Isle of Man, Volume III: the medieval period 1000-1406 (Editor, with Harold Mytum. Liverpool: Liverpool University Press, 2015), 606pp.
  • Brian Boru and the Battle of Clontarf (Dublin: Gill & Macmillan, 2013), 349pp
  • Princes, prelates and poets in medieval Ireland: essays in honour of Katharine Simms (Editor. Dublin: Four Courts Press, 2013), 599pp.
  • The English Isles: Cultural transmission and political conflict in Britain and Ireland, 1100-1500 (Editor, with Susan Foran. Dublin: Four Courts Press, 2013), 186pp.
  • The World of the Galloglass: Kings, warlords and warriors in Ireland and Scotland, 1200-1600 (Editor. Dublin: Four Courts Press, 2007), 219pp.
  • Medieval Ireland: An encyclopedia (Editor. New York & London: Routledge, 2005), 546pp.
  • Robert the Bruce’s Irish Wars: The invasions of Ireland, 1306-1329 (Editor. Stroud: Tempus Publishing, 2002), 221pp.
  • The Concise History of Ireland (Dublin: Gill & Macmillan, 2000), 256pp.
  • Ireland in the Middle Ages (Basingstoke & Dublin: Macmillan, 1997), 216pp.
  • Atlas of Irish history (Dublin: Gill & Macmillan), 2000), 60pp. [now in its 4th edn]
Duffy Books


  • ‘Gerald of Windsor and the origins of the Geraldines’, in Peter Crooks and Seán Duffy (eds), The Geraldines and medieval Ireland: the making of a myth (Dublin: Four Courts Press, 2016), pp 21–52
  • ‘Irish and Welsh responses to the Plantagenet empire in the reign of Edward I’, in Peter Crooks, David Green, and W. Mark Ormrod (eds), The Plantagenet Empire, 1259–1453, Harlaxton Medieval Studies XXVI (Donington: Shaun Tyas, 2016), pp 148–66
  • ‘The Welsh conquest of Ireland’, in Emer Purcell et al. (eds), Clerics, Kings and Vikings: essays on medieval Ireland in honour of Donnchadh Ó Corráin (Dublin: Four Courts Press, 2015), pp 103-114.
  • ‘Man and the Irish Sea World in the eleventh century’, in Seán Duffy and Harold Mytum (eds), A New History of the Isle of Man, Volume III: the medieval period 1000-1406 (Liverpool: Liverpool University Press, 2015), pp 9-26.
  • ‘The saint's tale’, in Sparky Booker & Cherie N. Peters (eds), Tales of Medieval Dublin (Dublin: Four Courts Press, 2014), pp 7-17.
  • ‘The Turnberry Band’, in Seán Duffy (ed.), Princes, prelates and poets in medieval Ireland: essays in honour of Katharine Simms (Dublin: Four Courts Press, 2013), pp 124-38.
  • ‘The “key of the Pale”: a history of Trim Castle’, in A.R. Hayden, Trim Castle, Co. Meath: Excavations 1995-8 (Dublin: Oifig an tSoláthair, 2011), pp 6-28.
  •  ‘The hermits of St Augustine in medieval Dublin: their history and archaeology’, in John Bradley et al. (eds), Dublin in the Medieval World: Studies in honour of Howard B. Clarke (Dublin: Four Courts, 2009), pp 202-48. [with Linzi Simpson]
  • ‘Ireland, c.1000-c.1100’, in Pauline Stafford (ed.), A companion to the early Middle Ages. Britain and Ireland c.500-c.1100 (London: Wiley-Blackwell, 2009), 285-302.
  • ‘Henry II and England's insular neighbours’, in Christopher Harper-Bill and Nicholas Vincent, eds, Henry II: New interpretations (Woodbridge: Boydell, 2007), pp 129–53.
  • ‘Town and crown: the kings of England and their city of Dublin’, in Michael Prestwich et al. (eds), Thirteenth Century England X (Woodbridge: Boydell, 2005), pp 95–117.
  • ‘The lords of Galloway, earls of Carrick, and the Bissets of the Glens: Scottish settlement in thirteenth-century Ulster’ in David Edwards (ed.), Regions and Rulers in Ireland, 1100-1650 (Dublin: Four Courts, 2004), pp 37-50.
  • ‘The British perspective’, in S.H. Rigby (ed.), A companion to Britain in the later middle ages (Oxford: Blackwell Publishers, 2003), pp 165-83.
  • ‘Historical revisit: Goddard Henry Orpen, Ireland under the Normans, 1169-1333 (1911-20)’, Irish Historical Studies, 37 (2000), 246-59.
  • ‘John and the origins of England’s Irish problem’, in S.D. Church (ed.), King John: new interpretations (Woodbridge: Boydell Press, 1999), pp 221-45.
  • ‘King John's expedition to Ireland, AD 1210: the evidence reconsidered’, Irish Historical Studies, 40 (1996), 1-24.
  • ‘The first Ulster plantation: John de Courcy and the men of Cumbria’, in Robin Frame et al. (eds), Colony and frontier in medieval Ireland: essays presented to J.F. Lydon (London: Hambledon Press, 1995), pp 1-27.
  • ‘Irishmen and Islesmen in the kingdoms of Dublin and Man, 1052-1171’, Ériu, 43 (1992), 93-133.
  • ‘The Bruce brothers and the Irish Sea world, 1306-29’, Cambridge Medieval Celtic Studies, 21 (1991), 55-86.

Teaching and Supervision

Professor Duffy currently teaches Sophister modules on ‘From Kingdom to Colony: Ireland in the Twelfth Century’ and on ‘Viking-Age Dublin’ and teaches and coordinates the following Freshman modules: ‘Kingship and Warfare: Ireland, 1000-1315’; ‘Early Christian Ireland, AD 400-800’; and ‘Doing History’.

At postgraduate level he teaches modules on the MPhil in Medieval History and supervises graduate students on all aspects of medieval Irish history.

Prof. Duffy on the TCD Research Support System

Contact Details

Room 3146
Department of History
Trinity College
Dublin 2.

Telephone: +353 1 896 1801
Fax: +353 1 896 3995