1 June 1866: American Fenians under General John O’Neill invade Canada and capture Fort Erie.

3 June 1866: American Fenians under O’Neill defeat English colonial forces at Ridgeway, Ontario. “British Square” broken.

The “British Square” was an iron-disciplined infantry formation that had withstood the charge of Napoleon’s cavalry at Waterloo in 1815 and which went on to develop a legend of being an unbreakable formation. Military analysts to this day repeat the legend of the “unbroken” British Square, oddly ignoring the outcome of the Battle of Ridgeway.

The Battle of Ridgeway was the last confrontation between European military forces in North America, and it came about as part of a revolutionary effort to liberate Ireland.

Following the collapse of the 1848 “Young Ireland” movement, the banner of Irish national independence was taken up anew in 1858 by the Fenian movement. Taking its name from the Fianna, the warrior-guardians of ancient Gaelic Ireland, the Fenians were conceived as a trans-Atlantic revolutionary conspiracy, drawing much of its strength and resources from the Irish immigrant community in the United States. The outbreak of the American Civil War in 1861 presented a rare opportunity to Fenian leaders in the United States, and regiments of Irish volunteers were recruited for the Union cause by officers who didn't try to conceal their ultimate goal of using the American conflict as a means of creating a trained force of veteran soldiers who would then return to liberate Ireland.

Never before, not even in the heyday of the “Wild Geese” had such an opportunity presented itself to the Irish. But the American Civil War lasted too long, and by the time most Fenian veterans were demobilized betrayals and swift action by the English authorities had already begun to compromise the Fenian movement in Ireland. In response to this series of setbacks the Fenian movement split, and one wing of the movement pursued a new and truly creative strategy: it would rearm and organize the recently demobilized Fenian Union army veterans (along with a few volunteers from the Confederate side) and invade southern Canada. Once in possession of a slice of southern Canada, the Fenians would proclaim an “Irish Republic in Exile” and perhaps use their occupation as leverage in negotiations with the English, or at least force the English to deploy troops to Canada they might otherwise use to suppress a revolt in Ireland.

The plans and preparations were hardly secret, nor could they realistically have been expected to be. But the Fenians got away with it because the US government was still mad at Queen Victoria’s government over English arms sales to the Confederacy and the building of such Confederate raiding ships as the Alabama and Shenandoah. Officials in Washington were therefore quite happy to turn a blind eye and let the Fenians go take a poke at the English lion. And Canada, still a year shy of its own Confederation, was still very much an English colony.

Setting out from the city of Buffalo and from various other points along the Niagara frontier, the Fenian army landed in Ontario and captured Fort Erie, ironically the scene of an American invasion in the War of 1812. From there they started to move northwards, their objective being the capture of the strategic Welland Canal that connects Lake Erie with Lake Ontario.

But only a few miles into Ontario they faced a hastily cobbled together force of Canadian militia at Ridgeway. A somewhat confused battle commenced, with the veteran Fenians having an edge against the courageous but inexperienced Canadians. The Canadian officers tried their best to do things by the book. Seeing a motion by some Fenian horsemen, they assumed that a cavalry charge was in the offing, and ordered their men to form the hollow squares that were guaranteed to foil cavalry attacks. Unfortunately the Fenians were really launching an infantry assault. The Canadians had misread their enemy, and once in the squares their men were at a marked disadvantage against infantry attacks, their frontal firepower being now only a quarter of what it had been in their previous line formation. Seasoned regulars might have been able to reform and hold their ground, but the green militiamen, disordered in their confused efforts to carry out a complex maneuver, fell apart and left the field to the Fenians.

It was a signal victory, but one which the Fenian leadership wasn’t prepared to follow up. Soon more and better crown forces were converging on southern Ontario, but the end came when US President Andrew Johnson’s administration decided they had gotten their snit’s revenge and moved to seal the border and interdict the flow of men and supplies to the Fenians in Canada. Caught out on a limb by this unexpected turnaround by the US government, the Fenian leadership decided on an abrupt withdrawal across the Niagara River to the US side.

Other incursions and threats of invasion by the Fenians would take place for years to follow, but the battle of Ridgeway was the high water mark of the Fenian invasion of Canada and of the attempt to establish an Irish Republic in Exile. But those who dismissed the Fenians as a farce were sorely mistaken. Continuing on through the Clan-na-Gael and the Irish Republican Brotherhood, the Fenian movement went underground and remained intact for another fifty years, emerging at last to launch the Easter Uprising of 1916.

The stories in This Month in Celtic History are drawn from over 1000 anniversaries of people and events from the histories of the six Celtic nations of Ireland, Scotland, Wales, Brittany, Cornwall, and the Isle of Mann in the annual Celtic Calendar, published by the Celtic League American Branch.