In 1314 he led the Maddens in concert with the Ui Maine under Tadhg Ó Cellaigh who were allied with Murtough O Brien in the civil war then devastating County Clare.
At the stronghold of the Ó Gradys, they did grievous killing ... women and boys and whole families included, whereby that murderous far secluded area became a mere heap of carnage thickly stacked.
Eoghan may have been present at the Second Battle of Athenry in 1316, where his brother John is recorded as among the dead.
In 1336 he engaged and defeated the Burkes of Clanricarde, killing three score and six ... both good and bad.
Eoghan was the recipient of a poem by Seán Mór Ó Dubhagáin (died 1372) which gave his pedigree and flattered Eoghan, stating that There is not a wood nor bog not plain/not a river nor bright-pooled lake/not a harbour from Caradh to Grian/which is not due to thee o tranquil faced youth.