Dermody is scholarly but lives hard and makes little of his life. At the age of nine he is employed as a classical teacher in his father’s school, and has already acquired from his father a love for literature and the bottle.
Dermody has the genius of a poet, and writes fairly good poetry, but his genius is not enough. He lives for 27 years, half his life a promising boy and half a ne’er-do-well. His promise brings him generous patrons in his early days in Ireland, but he scorns the hand that feeds him, denies the friends who could nurse his genius, and runs away to England to keep bad company.
At the age of nineteen, he enlists in the army and behaves uncommonly well under military discipline. He becomes corporal, sergeant, and eventually second lieutenant, serving with distinction. He is wounded in France, and upon his return to England, is retired on half-pay.
He gains and loses friend after friend and abuses patron after patron. They clothe and clean him and make him presentable, but he then drinks himself to nakedness and rags and behaves like a brute. Such from day to day and year to year is his life, and in the end he drinks himself to death and perishes in a miserable cottage near Lewisham on July 15, 1802. He is filled with conceit and a slave to his desires, but the lines that are fading away on the stone above his grave show that he was a poet. Dermody is buried in the churchyard of St. Mary’s Church Lewisham.
Dermody publishes two books of poems which, after his death, are collected as The Harp of Erin. Some 56 of his sonnets have been published in various works, from his first 1789 collection Poems to those published in 1792, with a few posthumously published verses in the biography by James Grant Raymond. Samuel Taylor Coleridge takes an interest in some of his verse which has been included in the literary magazine The Anthologia Hibernica.