German U-boats Invaded the St. Lawrence River in Canada

The Second World War's Battle of the St. Lawrence was a naval conflict that took place in a Canadian river. German U-boats managed to travel all the way up the river to Montreal, where they sank 23 ships over the course of many months. 70,000 tons of supplies were also lost by the Allies. The Nazis were far more powerful than the Canadians, who were ill-equipped to defend their own waterways against submarine raids. There were significant losses, and one ferry from Nova Scotia to Quebec sank while carrying women and children.

Since the river had never been a military target before, there was originally no aviation support at all, and there were hardly any defenses along it. Since the river had never been a military target before, there was originally no aviation support at all, and there were hardly any defenses along it. Defenses were ultimately installed, but it came at a high cost.