In December 1867 , O'Neill became president of the Roberts faction of the Fenian Brotherhood , which in the following year held a great convention in Philadelphia attended by over 400 properly accredited delegates , while 6,000 Fenian soldiers , armed and in uniform , paraded the streets . At this convention , the second invasion of Canada was conceived . The news of the Clerkenwell explosion was a strong incentive to a vigorous policy . Henri Le Caron , who , while acting as a secret agent of the British government , held the position of " Inspector-General of the Irish Republican Army , " asserts that he distributed fifteen thousand stands of arms and almost three million rounds of ammunition in the care of the many trusted men stationed between Ogdensburg , New York and St. Albans , Vermont , in preparation for the intended raid . It took place in April 1870 and proved a failure just as rapid and complete as the attempt of 1866 . The Fenians under O'Neill 's command crossed the Canadian frontier near Franklin , Vermont , but were dispersed by a single volley from Canadian volunteers . O'Neill himself was promptly arrested by the United States authorities acting under the orders of President Ulysses S. Grant
Clerkenwell explosion
Clerkenwell explosion
Fenian Brotherhood