German submarines in the Saint-Lawrence river?

Hello everyone.

I live in Quebec, Canada and I heard, a few times, that german submarines came in the Saint-Lawrence river in Québec, Canada. I would like to know more about these episodes.

What were they doing there? Where they spying, destroying merchant ships?

 

https://www.amazon.ca/Battle-St-Lawrence-Nathan-Greenfield/dp/0006394507

I read this book about 10 years ago. This is a good start.

 

Sorry don't know much about it but the u boats sank 23 merchant and naval ships. So I'd say creating havoc

 

Thanks for the link.

About the 23 merchant and naval ships sank by uboats, do you know if they were really in the Saint-Lawrence or in the Atlantic? Since I try not to spend more on books, if you find infos or links about that I would be very interested to know.

 

I believe most of them were in the Gulf of St. Lawrence rather than the river: Battle of the St. Lawrence - Wikipedia

Sinkings averaged about one per month, but they forced the Allies to corral merchant ships into convoys and to provide escorts for them. Many of these were Canadian-built minesweepers, but there were also frigates and corvettes that could otherwise have served on the Atlantic convoy routes.

WWII minesweepers commonly carried asdic and at least a few depth charges; some dispensed with minesweeping gear entirely in order to carry depth charge tracks and throwers and served as antisubmarine escorts. The open quarterdeck could accommodate either configuration.

 

Very interesting.

Question: What does "asdic" means exactly?

 

Early form of sonar, named for the "Anti-Submarine Detection Investigation Committee"