Here's a breakdown of some important milestones:
* 1500s: Leonardo da Vinci sketches designs for underwater vehicles, but none are built.
* 1620: Cornelis Drebbel, a Dutch inventor, builds a submersible that is successfully tested in the Thames River.
* 1776: David Bushnell builds the "Turtle," the first documented submarine used for military purposes.
* 1800s: Several inventors, including Robert Fulton, create submersibles, but they remain limited in capabilities and practicality.
* 1864: The Confederate submarine "H. L. Hunley" sinks a Union ship, becoming the first successful submarine attack in history.
* 1900s: The development of electric motors and improved materials lead to more advanced and reliable submersibles.
Therefore, depending on how you define "submersible," you could argue that:
* The earliest submersible was invented in the 1620s with Cornelis Drebbel's vessel.
* The first military submersible was created in 1776 with the "Turtle."
The continuous advancements and iterations throughout history make it difficult to pinpoint one definitive inventor or date.