About Arthur O'Neil
This is not the name of any known son of Shane O'Neil. He had one named Art - not Arthur - who escaped from Dublin Castle with Red Hugh O'Donnell in 1592, but died of exposure before reaching safety.
Arthur O'Neil would have been about twelve years old then.
Nor is "Anne" a name of any of Shane O'Neil's known wives - still less from within the same clan. He married exogamously and frequently in order to form political alliances.
There were by this time a lot of O'Neil(l)s with little or no genetic connection to the Ui Niall.
From Wikipedia: The sons of Shane – The Mac Shanes
Shane had at least ten sons by his various wives. All of these ten are considered legitimate, but there may be others of a base origin. Many of them were later fostered in various O'Neill clans after their father's death, and eventually became the rival force to Hugh O'Neill in his climb to power in the 1580-1600 timeframe. His known sons are:
- Shane Og, mother was Catherine MacDonnell. He died in 1581 on a raid, was tanist to the O'Neill, Turlough Luineach, in 1579.
- Henry MacShane O'Neill, His mother was Catherine MacDonnell, he died 1622. Father of Sir Henry O'Neill and Con Boy McHenry. Perhaps the most famous of Shane's sons. Granted a large Estate in Orior County Armagh.
- Con MacShane O'Neill, died in 1630. Mother was either the daughter of Shane og Maguire or Catherine MacLean, sources disagree. He invaded Ulster in 1583 with 3000 Scottish warriors and was named the Tanist of The O'Neill, Turlough Luineach, in the 1580s. During the 9 Years War, he fought against his cousin the Earl and was rewarded with a large estate (1,500 acres (6.1 km2)) and the Manor lordship of Clabbye in Fermanagh. He played a part in Ulster politics until his death in 1630/1. His sons continued to serve in Ireland and abroad. Two of his grandsons were made Spanish Counts.
- Turlough, mother was Catherine MacDonnell of the Route. Died 1598.
- Hugh Gaveloch, died in 1590, most popular of the Mac Shanes. Led an army of his MCLean kinsmen into Ulster to support his claim to The O'Neill Mór title. He was captured and hanged by his 1st cousin, Hugh, Earl of Tyrone.
- Naill, mother thought to have been Catherine O'Donnell.
- Art, mother was Catherine MacLean, died of exposure while escaping from Dublin Castle with Red Hugh O'Donnell [in 1592]. [Additional comment: "Art" is not derived from "Arthur" - it is an independent development. (See O Corrain & Maguire, Irish Names, p. 24 - this is a standard and mostly reliable resource for authentically Irish names.)]
- Brian Laighneach, mother was Catherine MacLean, died after 1598.
- Edmond, died fighting against Hugh O'Neill, Earl of Tyrone.
- Hugh McShane O'Neill, mother was Catherine MacLean, died in 1621. Became Chief of the O'Neill sept inside Glenconkeyne forest and known from that point on as the "MacShanes". (Sources point to the fact that Hugh may have been the son of Conn Mac Shane).
- Cormac, mother was Catherine MacLean, died after 1603. Stayed with brother Hugh MacShane as did his son Cormac Boy.
- Rose married into the MacDonnell clan.