When was the first submarine used in combat?

In 1776, The American Turtle, against the British HMS Eagle

For more information about the Turtle and/or the history of submarines, see:

Inventors.about.com

The Naval Historical Center

The Unmuseum

MayflowerFamilies.com

Notes:
The Unmuseum says "The first known submarine was the Drebbel built for James I of England in 1620. It operated in the Thames river and moved by use of oars that extended through sealed oarlocks."

Wikipedia, after describing the Turtle, states

Timeline of underwater technology

1716 - Edmund Halley builds a diving bell
1772 - Sieur Freminet builds the first scuba device, but dies from lack of oxygen after 20 minutes
1801 - Robert Fulton builds the first submarine
I don't know what they mean to say, but they are wrong.

And from http://www.chinfo.navy.mil/navpalib/cno/n87/history/subsaga2.html comes this about the Turtle's attack:
"Royal Navy logs and reports from this period make no mention of this incident, and it is possible that the Turtle's attack may be more submarine legend than historical event."