Fenianism (Irish: Fíníneachas), according to O'Mahony, is symbolised by two principles: firstly, that Ireland has a natural right to independence, and secondly, that this right could be won only by an armed revolution.
The term Fenianism was sometimes used by the [English] political establishment in the 1860s for any form of mobilisation among the Irish or those who expressed any Irish nationalist sentiments. They warned people about this threat to turn decent civilised society on its head such as that posed by trade unionism to the existing social order in the United Kingdom.
James Stephens, one of the "Men of 1848," (a participant in the 1848 revolt) had established himself in Paris, and was in correspondence with John O'Mahony in the United States and other advanced nationalists at home and abroad. This would include the Phoenix National and Literary Society, with Jeremiah O'Donovan (afterwards known as O'Donovan Rossa) among its more prominent members, had recently been formed at Skibbereen.
Along with Thomas Clarke Luby, John O'Leary and Charles Kickham he founded the Irish Republican Brotherhood on 17 March 1858 in Lombard Street, Dublin.
The Fenian Rising in 1867 proved to be a "doomed rebellion," poorly organised and with minimal public support. Most of the Irish-American officers who landed at Cork, in the expectation of commanding an army against England, were imprisoned; sporadic disturbances around the country were easily suppressed by the police, army and local militias.
In 1882, a breakaway IRB faction calling itself the Irish National Invincibles assassinated the British Chief Secretary for Ireland Lord Frederick Cavendish and his secretary, in an incident known as the Phoenix Park Murders.
The Fenian Brotherhood, the Irish Republican Brotherhood's US branch, was founded by John O'Mahony and Michael Doheny, both of whom had been "out" (participating in the Young Irelander's rising) in 1848. In the face of nativist suspicion, it quickly established an independent existence, although it still worked to gain Irish American support for armed rebellion in Ireland. Initially, O'Mahony ran operations in the US, sending funds to Stephens and the IRB in Ireland, disagreement over O'Mahony's leadership led to the formation of two Fenian Brotherhoods in 1865. The US chapter of the movement was also sometimes referred to as the IRB. After the failed invasion of Canada, it was replaced by Clan na Gael.
In Canada, Fenian is used to designate a group of Irish radicals, a.k.a. the American branch of the Fenian Brotherhood in the 1860s. They made several attempts to invade some parts of the British colonies of New Brunswick (i.e., Campobello Island) and Canada (present-day Southern Ontario and Missisquoi County), with the raids continuing after these colonies had been confederated. The ultimate goal of the Fenian raids was to hold Canada hostage and therefore be in a position to blackmail the United Kingdom to give Ireland its independence. Because of the invasion attempts, support and/or collaboration for the Fenians in Canada became very rare even among the Irish.
Francis Bernard McNamee, the man who started the Fenian movement in Montreal (and who was later suspected of being a government spy), was a case in point. In public, he proclaimed his loyalty to the queen and called for an Irish militia company to defend Canada against the Fenians. In private, he wrote that the real purpose of an Irish militia company would be to assist the Fenian invasion, adding for good measure that if the government denied his request he would raise the cry of anti-Irish Catholic discrimination and bring more of his aggrieved countrymen into the Fenian Brotherhood.
A suspected Fenian, Patrick J. Whelan, was hanged in Ottawa for the assassination of Irish Canadian politician, Thomas D'Arcy McGee in 1868, who had been a member of the Irish Confederation in the 1840s.
The danger posed by the Fenian raids was an important element in motivating the British North America colonies to consider a more centralised defence for mutual protection which was ultimately realised through Canadian Confederation.
The Fenians in England and the Empire were a major threat to political stability. In the late 1860s the IRB control centre was in Lancashire. In 1868 the Supreme Council of the IRB, the provisional government of the Irish Republic, was restructured. The four Irish provinces, Connacht, Leinster, Ulster and Munster, Scotland, the north of England and the south of England, including London, had representatives on the Council. Later four honorary members were co-opted. The Council elected three members to the executive. The President was chairman, the Treasurer managed recruitment and finance and the Secretary was director of operations. There were IRB Circles in every major city in England.
On 23 November 1867, three Fenians, William Philip Allen, Michael O'Brian, and Michael Larkin, known as the Manchester Martyrs, were executed in Salford for their attack on a police van to release Fenians held captive earlier that year.
On 13 December 1867, the Fenians exploded a bomb in attempt to free one of their members being held on remand at Clerkenwell Prison in London. The explosion damaged nearby houses, killed 12 people and caused 120 injuries. None of the prisoners escaped. The bombing was later described as the most infamous action carried out by the Fenians in Great Britain in the 19th century. It enraged the public, causing a backlash of hostility in Britain which undermined efforts to establish home rule or independence for Ireland.
In Northern Ireland, Fenian is used by some as a derogatory word for Catholics; in 2012, British National Party leader Nick Griffin was criticised by Unionists and Republicans for tweeting the term while attending an Ulster Covenant event at Stormont, Belfast; Griffin referred to Lambeg drums, saying "the bodran [sic] can't match the lambeg, you fenian bastards".
The term Fenian is used similarly in Scotland. During Scottish football matches it is often aimed in a sectarian manner at supporters of Celtic F.C.. Celtic has its roots in Glasgow's immigrant Catholic Irish population and the club has thus been associated with Irish nationalism, symbolised by the almost universal flying of the Irish Tricolour during matches. Other Scottish clubs that have Irish roots, such as Hibernian and Dundee United, do not have the term applied to them, however. The term is now firmly rooted within the Old Firm rivalry between Celtic and Rangers, as a rivalry between "orange and green" has been replaced by one between "blue and green".
In Australia Fenian is used as a pejorative term for those members of the Australian Labor Party (ALP) who have Australian Republican views similar to those who support Irish unification. Michael Atkinson, Attorney-General of South Australia, spoke of those members of the ALP who wished to remove the title Queen's Counsel and other references to the crown as "Fenians and Bolsheviks" in a speech given at the ALP Convention in Adelaide on 15 October 2006. Atkinson made a further mention of Fenianism when the title of Queen's Counsel was abolished.'The Fenians were the best men in Irish politics.' Attributed to Isaac Butt, B. O'Brien, The Life of Charles Stewart Parnell, 1846—1891, p. 63
'The Fenian is the artist in Irish politics. He is an inspiration, an ornament, a hero.' Liam O'Flaherty, The Life of Tim Healy (1927)p. 40.
' ... the fools, the fools, the fools! They have left us our Fenian dead, and while Ireland holds these graves, Ireland unfree shall never be at peace.' Padraig Pearse's graveside oration at the reinterment of Jeremiah O'Donovan Rossa's remains in Glasnevin Cemetery in August 1915.
'We may have brave men, but we'll never have better. Glory O, Glory O, to the bold Fenian men.' Down by the Glenside, Peader Kearney, 1916
In Anthony Trollope's The Eustace Diamonds (1873), Lord George de Bruce Carruthers, an Irish peer, is a man about town with no visible means of income. He is 'a bitter radical' and 'was suspected even of republican sentiments, and ignorant young men about London hinted that he was the grand centre of the British Fenians.' A full description follows.
Arthur Conan Doyle's 'Touch and Go: A Midshipman's Story', was published in 1886, the year the First Home Rule Bill was introduced in the House of Commons. Set in 1868, a young midshipman and his two companions are shipwrecked on the Irish Sea. A launch carrying the IRB leader, the 'Fenian head-centre' James Stephens, 'a middle-aged man in dark clothes and a grey overcoat', rescues them. Stephens puts the young midshipman and his friends ashore on the Isle of Man and asks for their silence.
Joseph Conrad's The Secret Agent, published in 1907 but set in 1886, takes place against the background of terrorist bombings in Britain. Although Conrad's bombers are anarchists, most critics agree that the Fenian bombings are a significant part of his inspiration, especially as international anarchist terrorism in the nineteenth century had had comparatively little impact in Britain compared to the Fenian campaigns.
In the 2011 Christmas Day Special of the television series Downton Abbey, Lord Grantham, after learning of the pregnancy of his daughter Sybil, who is married to an Irish revolutionary, says, "So, we're to have a Fenian grandchild." His wife, Lady Grantham, replies, "Cheer up. Come the revolution, it may be useful to have a contact on the other side."
In the 2014 Christmas Day Special of the television series Downton Abbey, Mr. Stowell, Lord Sinderby's butler, condescendingly wonders if Mr. Branson would be picking up the grouses or reading Motor magazine when the others are shooting. Upon hearing that he is, in fact, a very good shot, Stowell remarks "Is he, indeed? I suppose that was his training with The Fenians", with obvious disdain for both Branson's Irish nationalism and his previous employment as a low-ranking chauffeur.
In the 2014 film '71 Fenian is used to describe the extremist youth of the IRA.
The term is used in the movie Patriot Games. In the movie, when captured after a botched attempt against a Royal's life, a separatist group member is interrogated, and during this period is slapped and called a "Fenian bastard" by one of his British captors.
Down by the Glenside (The Bold Fenian Men) is an Irish rebel song written by Peadar Kearney, an Irish Republican and composer of numerous rebel songs, including "The Soldier's Song" ("Amhrán na bhFiann", the chorus of which is now the Irish National Anthem) and "The Tri-coloured Ribbon".
The term is frequently used in the BBC's 2013 Series Peaky Blinders. in the series, a family of 1920's Birmingham gangsters are pursued by Major Chester Campbell, a police officer reassigned from his Belfast home to deal with Birmingham's criminality, who applies the strategies he had previously used in repressing Republican agitation in Ireland.