Earliest Submarine Warfare

Everyone knows about da Vinci's designs for flying machines and tanks, but his dabbling in submarines is often overlooked. He designed a submersible craft and a diving suit which he presented to the Republic of Venice (naturally, it was turned down). Then after a brief interest in the 16th century, it seems that with the exception of the American Revolutionary War the ideas fell by the wayside until the 19th century, and even then, the idea was met with polite indifference until the 1890s.
http://didyouknow.org/submarine/
So what I'm wondering is what is the earliest plausible date we can establish bubbleheads as part of the armed forces. Obviously, this would require a sustained interest in the idea of underwater warfare rather than it moving by fits and starts as OTL. Also, who would be most likely to be the first country (Venice? England? The United Provinces? France? Someone else?) to takes this idea seriously?
 
Without a reliable way of powering a submarine/submersible while submerged and providing an adequate air supply, submarines could never become a significant element of any major nation's naval strategy until the late 19th early 20th century (ie when they first became practical OTL). Examples like the CSS Huntley and Bushnell's Turtle are the most likely way a submarine might be used earlier. The problem with all the early submarines, they were essentially weapons of desperation in assymetric naval wars. Kinda like nautical IEDs or suicide bombers (which operational submarines pretty much were in the 18th and 19th centuries). So if anybody seriously tried to develop and use man-powered subs, it would probably not be any major naval power but instead a smaller power or rebellious group (perhaps even non-western one) that felt oppressed and victimized by major naval powers. Major navies, like the Royal Navy, had every reason not to be interested. They ruled the waves so they didn't need to skulk around under them trying to sink the enemy's ships with screws or spar torpedoes. I suppose primitive submersibles might be somewhat useful as a means of landing small detachments of men or supplies ashore in enemy territory, but then again this really wasn't all that hard by rowboat under cover of darkness in the 18th century. I've read my CS Forrester.
 
Some American engineer (well, I hope he was an engineer) (ok, not an engineer, Wikipedia names him as Samuel William Taber) proposed it to the Not-Yet-Argentine government during the early 1810s as a way to counter the Spanish fleet based at Montevideo. It was initially approved, but war and politics postponed and eventually canceled the project.
Throw in a few butterflies and it could have been built. Whether it would have worked or not, OTOH...
 
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