Of course, that did not happen.
One thousand Canadian troops attacked. After a short, disorderly battle, the Fenians scattered. "They fired only a single full volley when the advance began" (Seaver 674). All these shots, and the few rounds that followed, all flew over the heads of the Canadian troops.
Only a few injuries resulted overall, so the Canadians were not much better prepared.
The fleeing Fenians escaped over the border, and the Canadian troops did not follow.
And the fleeing scene is something worthy of a Hollywood comedy. The Fenians swarmed Trout River, ran to Leahy's far and continued on back to Malone throwing away their armaments, or battering them away for food, as they scattered.
On May 28, back at the Fairgrounds, some officers tried to rally the troops for another attack. Hungry and tired, the refused. This appears to be good for them as one thousand US regulars arrived the next morning and would have suppressed the attack.
As a result of the battle, no Canadians were killed, Three or four Fenians were wounded, and one was taken prisoner. According to Seaver, the Fenians themselves were good fighters, but their leadership lacked talent.
Seaver, Fredrick. Historical Sketches of Franklin Countly. Albany: JP Lyons, 1918.