The Confederates had a submarine, and it worked.
The CSS Hunley may have been the first submarine to sink an opposing ship.
Unfortunately successful delivery of the "torpedo" was likely fatal to the crew.
Who knew that 16' of separation between the sub and target; with 160 lbs of blackpowder as the charge; just wasn't enough...

https://arstechnica.com/gadgets/2017...earchers-find/