His father Tomás Óg 'na Fésóige' Mág Samhradháin, the Third, was chief of the clan until his death in 1458.
On Tuesday 27 September 1485 Ballymagauran was burned during a raid by the O’Reilly clan but the McGoverns retaliated.
The latter part of Feidhlimidh's reign was troubled by internecine warfare between him and his relations in a struggle over the chieftainship.
The Annals of Ulster for 1486 state- A skirmish took place between the Tellach-Eathach themselves, wherein was slain Feidhlimidh, son of Ferghal Mag Samradhain.
During the same year an Irish translation (Togail na Tebe) of a Roman poem from 91 A.D., the Thebaid by Publius Papinius Statius was transcribed by Diarmaid Bacach mac Parthalain (Dermot "The Lame" MacPartland).
Feidhlimidh had a stronghold on a crannog in Killywillin Lough and he met his death while there on Sunday 15 February 1495.
The Annals of the Four Masters for 1495 state- Magauran (Felim, the son of Thomas, son of Brian Breaghach), Chief of Teallach-Eachdhach (Tullyhaw), was drowned in Loch-Crannoige of Caill-an-mhuillinn; and Donnell Bearnagh, his brother, took his place.