10/5/2012:
Horace Greeley ordered Americans to "Go west, young man," and a group of U.S. leaders, called Annexationists, wanted to take this one step further by annexing Canadian lands and connecting Alaska to the Pacific Northwest. A rebellion in Manitoba seemed to be the opportunity the Annexationists needed.
Irish priest William O'Donoghue was secretary to the Metis leaders during the Red River Rebellion of 1870. This attempt to reclaim Metis native lands in Manitoba crumbled in early 1871 when Fort Garry was taken back by Canadian troops. O'Donoghue fled to Pembina, Dakota Territory, and found support with the Annexationists, who hoped O'Donoghue would spearhead another rebellion, giving the Annexationists an opening to claim Manitoba, and the west, for the U-S.
Annexationist Congressmen from Michigan, Minnesota, and Massachusetts brought O'Donoghue to Washington D.C. to gain support for the rebellion, but no one wanted to start a conflict with Canada. In June 1871, O'Donoghue found support with the only other group to invade Canada and hold their ground – the Fenian Brotherhood, an Irish group.
The Brotherhood believed their invasions into Canada would help earn Ireland's independence from England. General John O'Neill, president of the Fenians, had just been released from jail for his latest armed attack on Canada when he met William O'Donoghue. O'Donoghue promised the support of the Metis rebels, O'Neill offered the Fenian army, and they believed their combined forces would succeed in liberating Manitoba.
The invasion was planned in Saint Paul in September 1871. The rebels drafted a compact to establish a joint government run by the Irish Fenians and the native Metis. The Fenians, of course, would control the military, and O'Donoghue would be made the first president. Shortly after the ink was dry, the invaders headed west.
When O'Donoghue, O'Neill, and a few dozen supporters arrived in Pembina, they didn't realize their plans were unraveling. The Metis chose to honor their peace agreement with Canada and the Fenians disavowed any military action. O'Neill's trusted aide, who had been ordered to muster the troops, was actually a Canadian spy. Canadian Magistrate Gilbert McMicken arrived in Dakota and authorized Colonel Wheaton at Fort Pembina to arrest the invaders if they crossed into Canada.
As the small group of invaders marched north to the Canadian border on October 5th, O'Neill and O'Donoghue were each hoping the other's army would arrive soon … armies that didn’t exist! When the U.S. troops from Pembina caught up with the invaders, O'Neill's men promptly surrendered. The failed invasion had the opposite effect of what the Annexationists hoped: the cooperation of the U.S. and Canada to suppress the invasion strengthened ties between the two countries, and it affirmed Canada's control over the young provinces along the U.S. border.
Dakota Datebook written by Derek Dahlsad
Sources:
“Chapter II: …and a Tale of Two Railroads”, http://www.dickshovel.com/two2.html
"The Creation of Manitoba", Alexander Begg
“Dictionary of National Biography, Volume 1”, Sir Leslie Stephen
“A Firey Fenian", Winnipeg Free Press, 12-25-1895
“The Abortive Fenian Raid on Manitoba, Account by One Who Knew Its Secret History”, Hon. Gilbert McMicken