St Albans was also the headquarters of an attempted Fenian invasion of Canada in 1870.
From the age of 13 he belonged to the Canadian volunteer militia, with which he saw service in 1870 at the time of the Fenian raids.
The close of the American Civil War, the Fenian raids across the American border, and the dangers incident to the international situation, gave a decisive impulse to the movement.
In 1867 the most serious of modern conspiracies, that known as the Fenian organization, came to light.
His murderer, a Fenian acting under the instructions of the secret society to which he belonged, was discovered, and executed in 1869.
On the other hand, Canadian feeling had been equally exasperated by the Fenian raids, organized on American soil, which had cost Canada much expenditure of money and some loss of life.
Much to the annoyance of the people of the Dominion the claims for the Fenian raids were withdrawn at the request of the British government, which undertook to make good to Canada any losses she had suffered.
An imperial guarantee of a loan for the construction of railways was the only compensation Canada received for the Fenian raids.
Numerous parallels exist between the Arthurian and early Irish heroic cycles, notably the Fenian or Ossianic. This Fenian cycle is very closely connected with the Tuatha de Danaan, the Celtic deities of vegetation and increase; recent research has shown that two notable features of the Arthurian story, the Round Table and the Grail, can be most reasonably accounted for as survivals of this Nature worship, and were probably parts of the legend from the first.
In 1865, through a companion in arms named O'Neill, he was brought into contact with Fenianism, and having learnt of the Fenian plot against Canada, he mentioned the designs when writing home to his father.
He was a proficient in medicine, among other qualifications for this post, and he remained for years on intimate terms with the most extreme men in the Fenian organization under all its forms. His services enabled the British government to take measures which led to the fiasco of the Canadian invasion of 1870 and Riel's surrender in 1871, and he supplied full details concerning the various Irish-American associations, in which he himself was a prominent member.
He saw active service during the Fenian raid of 1866, and during the rebellion of 1885.
After some years of newspaper experience, first as compositor, then as reporter, during which he became an ardent revolutionist and joined the Fenian organization known as the Irish Republican Brotherhood, he enlisted in a British cavalry regiment with the purpose of winning over the troops to the revolutionary cause (1863).
At this period wholesale corruption of the army, in which there was a very large percentage of Irishmen, was a strong feature in the Fenian programme, and O'Reilly, who soon became a great favourite, was successful in disseminating disaffection in his regiment.
The same course was adopted in Ireland in 1866 during a Fenian rising.
A prison erected here at this period gave place later to the House of Detention, notorious as the scene of a Fenian outrage in 1867, when it was sought to release certain prisoners by blowing up part of the building.
At the beginning of 1866 Lord Russells government thought itself compelled to suspend the Habeas Corpus Act In Ireland; and in 1867 Lord Derbys government was confronted in the spring by a plot to seize Chester Castle, and in the autumn by an attack on a prison van at Manchester containing Fenian prisoners, and by an atrocious attempt to blow up Clerkenwell prison.
So far as Arthur himself is concerned these parallels are with the Fenian, or Ossianic, cycle, in the case of Gawain with the Ultonian.
Irish disaffection had long been astir; the Fenian menace looked formidable not only in Ireland but in England also.
The Fenian movement disclosed much discontent, and was attended by criminal outrages in England.
The Fenian element was with him, as he admitted, but the clergy were against him, and the odds were too great, especially against a Protestant politician.