October 10-12, 1864, 21 confederate soldiers snuck across the border from Quebec, a few at a time, into Vermont with plans to rob 3 Franklin County banks in the name of the Confederacy. They scouted out the banks and planned to rob them on the 18th, but there were too many people in town, so they postponed until the 19th. The first bank they went after was the St. Albans bank (picture to the left) and they announced that they were Confederates, were going to take the town and shoot the first person to resist. This was ignored at first as a prank. They proceeded to rob the St Albans bank, and the people in the bank, before making them swear allegiance to the Confederate States of America.
Nine of the men took control of the town while the robberies were occurring, but it wasn't long
before the town began to fight back. Captain George Conger (photo on the left) of the 1st Vermont Infantry Regiment, who was on leave, raised the alarm and organized the resistance and posse. They forced the Confederate bank robbers to leave town and the robbers crossed the Missisquoi river back into Canada. 13 of the men were promptly captured by Canadian Police. The rest were chased across the border by Captain Conger and his mob before being captured. The mob started to attack the Confederates, but the whole thing was broken up by a British officer, who kicked Capt. Conger and mob out of the country. The bank robbers were eventually let go, since the American civil war wasn't a British or Canadian problem. The US demanded they hand over the prisoners, but the Canadian courts ruled that the soldiers were under military orders, so they would not extradite them, however, most of the money was returned ($88,000, about 1.4 million today).
The ironic end to this is that the Canadian people became upset with the Confederacy for, in effect, dragging them, against their will into civil war. This stopped any further actions across the norther border of the US.
There is a lot more detail to this robbery, so here is a link to a more in depth story: http://www.stalbansraid.com/history/the-raid/