Patrick Denis O'Donnell

Later, he held senior responsibilities in the Observer Corps (the Irish Army's unit for mitigation and preparedness in the event of nuclear war), military intelligence, and border security.

He was very active in O'Donnell Clan research for many decades, and at one time represented the Irish Defence Forces and the Military History Society in these matters.

He also researched Theobald Wolfe Tone's death, discovered his tomb, and published several articles on evidence that it was an assassination rather than suicide.

Some of his written material on military technology has been used for instructional purposes at the US Armed Forces Staff College in Norfolk, Virginia.

He also held the position of Hereditary Lord Steward for Tyrconnell, with prerogatives as deputy to the Lord High Steward of Ireland (Great Seneschal of Ireland)[1][2] and also succeeded to an Irish territorial barony, Fingal[3][4] originally dating back to a grant by King John in 1208[5] and a related manorial lordship, Fyngallestoun.

Patrick Denis O'Donnell died in Beaumont Hospital, Dublin, after a long illness, and his remains were interred in Glasnevin Cemetery, following a funeral with military honours and a pall-bearer party from the 5th Infantry Battalion, whose insignia he designed, and in the presence of the Chief of Staff, Lt. General James Sreenan, and accompanied by surviving family members, relatives and friends.