Deniehy was born in Sydney, the son of Henry and Mary Deniehy, former convicts of Irish birth who had prospered in the colony after their term had expired. Deniehy was educated at the best schools Sydney then had to offer, including Sydney College, and completed his education in England at his father's expense. He travelled in Europe and visited Ireland, where he met leaders of the Young Ireland party. He was influenced by both English Chartism and Irish nationalism. Returning to Sydney in 1844, he studied law and became a solicitor in 1851.
Meanwhile Deniehy became a leading figure in Sydney's small but lively literary world and in radical politics; artist Adelaide Ironside was an associate. Deniehy was a follower of the radical leader John Dunmore Lang (despite Lang's violent dislike of the Irish and of Roman Catholicism), and a member of Lang's organisation, the Australian League. He practised law in Goulburn 1854–58, in Sydney 1858–62, in Melbourne 1862–64 and in Bathurst 1865. In all these places he was active in local politics and journalism.
Like Lang, Deniehy was an advocate of extended democracy in the emerging political systems of the Australian colonies. He joined the opposition to the 1853 New South Wales Constitution Bill, which would have created a powerful unelected upper house and limited the franchise for the lower house to those owning substantial property. He was active in the New South Wales Electoral Reform League, which advocated manhood suffrage for the lower house and reduced powers for the upper house.
Deniehy argued that the real issue was control of the vast grazing lands of inland New South Wales, which the squatter class of early settlers had seized for themselves. He accused the conservatives, led by the veteran Sydney politician William Wentworth and what Deniehy called "some dozen of his friends," of wanting to "confiscate for their own uses the finest portions of the public lands, to stereotype themselves into a standing government, so that they may retain, watch over, and protect the booty they wrest."
When Wentworth proposed creating a hereditary peerage in New South Wales, Deniehy savagely satirised it: "Here," he said, "we all know the common water mole was transferred into the duck-billed platypus, and in some distant emulation of this degeneration, I suppose we are to be favoured with a "bunyip aristocracy." (The bunyip is a mythical beast of Aboriginal legend.) His ridicule caused the idea to be dropped.
Deniehy was elected to the New South Wales Legislative Assembly in 1857, representing Argyle (the Goulburn region). In 1859 he stood for West Sydney, but was defeated. However he was successful in 1860 representing East Macquarie (the Bathurst region). As a radical democrat, he should have been an effective supporter of the liberal parliamentary leaders Charles Cowper and John Robertson. But he disliked both these leaders, and was temperamentally unable to work in a parliamentary team. He soon became an isolated loner, and began to drink heavily. With the introduction of manhood suffrage in New South Wales in 1858 his campaign for democracy was fulfilled, and he was out of sympathy with the more advanced radicals.
Members of Parliament were not paid at this time, and Deniehy always earned his living as a barrister and as a journalist. He founded and edited Southern Cross, a radical newspaper, in 1859. Deniehy had opposed the appointment of Lyttleton Bayley as attorney-general and produced a satire How I Became Attorney-General of New Barataria (Sydney, 1860) which was published in the Southern Cross. In Melbourne in 1862 he edited The Victorian for its owner, the Irish-Australian politician Charles Gavan Duffy. In Sydney he became a notable literary critic, and lectured on modern literature at the newly founded Sydney University. He was a regular contributor to the Irish-Australian newspaper The Freeman's Journal and other papers.
Only 150 cm (five-foot) tall and in poor health throughout his life, Deniehy possessed enormous energy and was a gifted orator. The Australian historian Manning Clark writes of him: "His heart was a battlefield between the cherub and the insect of sensual lust." (He married Adelaide Hoals in 1852 and had seven children in nine years). "At times his face caught a fire and beauty that looked like phases of actual transfiguration. At other times his face was coarsened by days of drunken debauchery." He died of alcoholism in Bathurst, aged only 37. In 1895 his remains were exhumed and reburied in Sydney's Waverley Cemetery, where a monument was erected over the grave. An inscription on it reads:
- The vehement voice of the South
- Is loud where the journalist lies
- But calm hath encompassed his mouth,
- And sweet is the peace in his eyes.
- E.A. Martin, The Life and Speeches of Daniel Henry Deniehy (1884)
- Cyril Pearl, Brilliant Dan Deniehy: a Forgotten Genius (1972)
- Walsh, G. P. "Deniehy, Daniel Henry (1828–1865)". Australian Dictionary of Biography. Canberra: Australian National University. Retrieved 24 August 2012.
- Percival Serle (1949). "Deniehy, Daniel Henry". Dictionary of Australian Biography. Angus & Robertson. Retrieved 15 August 2009.
Additional sources listed by the Australian Dictionary of Biography:
- G. B. Barton, Literature in New South Wales' (Sydney, 1866); G. B. Barton (ed), The Poets and Prose Writers of New South Wales (Sydney, 1866); E. A. Martin, The Life and Speeches of Daniel Henry Deniehy (Melbourne, 1884); J. Normington-Rawling, Charles Harpur: An Australian (Sydney, 1962); P. Loveday and A. W. Martin, Parliament Factions and Parties (Melbourne, 1966); B. T. Dowd, 'Daniel Henry Deniehy', Journal of the Royal Australian Historical Society, 33 (1947); Austral Light, Apr 1894; Sydney Morning Herald, 16 August 1853, 19 February 1857, 5, 13 Jan 9, 28 Feb 4 March 1859, 27 October 1865; Freeman's Journal (Sydney), 19 March 1859, 28 October 1865, 13 May 1883; Australian Journal, Oct 1869; Bulletin, 15 April 1882, 1–29 Sep, 6 October 1888; Town and Country Journal, 17 March 1888; Henry Parkes letters (State Library of New South Wales).
Additional sources listed by the Dictionary of Australian Biography, not listed above:
- E. A. Marlin, The Life and Speeches of Daniel Henry Deniehy; G. B. Barton, Literature in New South Wales, pp. 55–63; W. B. Dalley, Introduction to reprint of Deniehy's The Attorney-General of New Barataria; The Bulletin, Red Page, 17 September 1898; Aubrey Halloran, Journal and Proceedings Royal Australian Historical Society, vol. XII, pp. 341–5.
- Daniel Henry Deniehy by the Australian poet Henry Kendall
- A downloadable text of The Life and Speeches of Daniel Henry Deniehy
- Mennell, Philip (1892). " Deniehy, Daniel Henry". The Dictionary of Australasian Biography. London: Hutchinson & Co. Wikisource
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