John L, as he was so well known, had been Captain of "L" Company, 2nd Battalion, 3rd Cork Brigade of the Old IRA during the War of Independence. He also served as Captain in the Irish National Army from 1922 to 1925. He was a Fine Gael TD for the constituency of Cork South-West and a member of Cork County Council for many years.
To counteract the lies that continue to be propagated by certain elements of the subversive kind, in respect of the Irish Plenipotentiaries who negotiated the Anglo-Irish Treaty in December 1921, I will reproduce an excerpt from George Cronin's report following his conversation with John L. O'Sullivan:
....One of the points made by John L during my meeting with him was that the general public are not aware of the powers given to the plenipotentiaries when they were discussing the Treaty.
"These two copy documents (which he handed me) make it quite clear", he said, "that the plenipotentiaries had full power to negotiate and to conclude an agreement with the British".
The first, signed by Eamonn de Valera as President, reads:
In virtue of the authority vested in me by Dail Eireann, I hereby appoint Arthur Griffith TD, Minister for Foreign Affairs, Chairman; Michael Collins TD, Minister of Finance, Robert C. Barton TD, Minister for Economic Affairs; Edmond J. Duggan TD; George Gavin Duffy TD, as envoys plenipotentiary from the elected government of the Republic of Ireland to negotiate and conclude on behalf of Ireland with the representatives of his Britannic Majesty, George V, a treaty or treaties of settlement, association and accommodation between Ireland and the community of nations known as the British Commonwealth" (done in the City of Dublin this 7th day of October in the year of Our Lord 1921 in five identical originals).
The second was an extract from Piaras Beaslai's book, Michael Collins and the Making of a New Ireland. This read:
When De Valera proposed his five plenipotentiaries—Arthur Griffith, Michael Collins, Robert Barton, Eamonn Duggan and George Gavan Duffy—for ratification to the private session of the Dail, Miss McSweeney and Joseph McDonagh sought to have conditions imposed on the delegates.
Mr. De Valera strenuously objected to this course. He insisted that they be plenipotentiaries without any limitations to their terms of reference.
"The Dail", he pointed out, "would have sufficient safeguard in the fact that any agreement signed by them would have to be submitted to the Dail for ratification".
"Remember what you are asking them to do", he said emphatically. "You are asking them to secure by negotiations what we are totally unable to secure by force of arms".
On this point he overbore all opposition and Mr. McDonagh withdrew his proposal, declaring himself satisfied.