alternatehistory.com

10 August

A Fenian plot activates, having managed to remain largely secret from intelligence in British North America and in the United States - in part because the rank-and-file of the Fenian force has not been informed of the precise details of the plan. Two companies of Fenians cross the border near Rouses Point, and seize the station at Lacolle as their first course of action.
By the afternoon the news is out, and one of the garrison regiments currently in Canada (the 39th Foot, in and around Montreal) is made ready to move south. Also already gathering are a large number of militia, including some regiments currently embodied for yearly training.

Also on this date, the new US lakes gunboat the Niagara Falls suffers a major engineering casualty, with a catastrophic boiler explosion taking place during routine operations.


11 August

Over the course of the day, nearly 2,500 Fenian infantry cross the Niagara river. The Niagara Falls is unable to intercept due to the severe damage to her boiler, which it will later turn out was the result of deliberate sabotage - Fenian sympathizers among the crew having placed a number of "coal torpedoes" into the bunker the previous morning. (Coal torpedoes being essentially camouflaged iron bombs filled with gunpowder and made to look like common lumps of coal.)

The news of the crossing is hurriedly relayed throughout British North America. Some of the militia undergoing training in the area had been moving towards the Richelieu frontier, and so the reorientation to the Niagara is chaotic and confused - some regiments travel all the way to Montreal before discovering that they have been ordered back to where they started.
Compounding the problem is that the scale of Fenian commitment to the operation is completely unclear. Some rumors have the Fenian brigade in Niagara on the scale of a division or even a small corps, others suggest they have considerable artillery with them, and their weaponry is the subject of wild speculation. (In fact, the Fenians are armed with Springfield rifles, and they have one old 6 pounder with them.)


12 August

The British/Canadian response to the Fenian attack near Niagara has begun to gel. Unsure of the scale of the filibuster operations (at either location) the British are opting for a provision of considerable force in both regions.

While the main force is still forming up (consisting of militia who are being quickly mobilized), the 1/14th is to probe towards Fort Erie (currently under Fenian control) from the still-secured town of Welland, to act as a screen. The experienced men of the Buckinghamshire regiment spread out into the now-classic British advance to contact, spreading three companies out as skirmish elements and another three companies as support elements.
In a classic example of mirror-imaging, the British (expecting to fight a large force) are on the lookout for possible cavalry pickets, while the Fenians against whom they are advancing (expecting a small force this early in the operation) are watching for Canadian militia. In the event, a firefight briefly breaks out around Stevensville, before the 1/14th withdraw a few hundred yards to make use of small local terrain features.

Once the news has percolated through the Fenian command, it causes mixed reactions. Some among the filibusters see this as a major opportunity to score a victory, and advocate for a rapid advance and the encirclement the enemy force; others are having second thoughts about the whole enterprise (especially as it appears the locals are for the most part not especially glad to be liberated), and more than a few quietly slink off (though they are replaced by stragglers filtering across the Niagara).

In the event, the decision is made to close in and attack the 1/14th - though, even as this discussion is going on, the 1/14th is withdrawing by night towards Netherby and two Canadian militia battalions are marching to join them there.