Gunpowder Incident

The Gunpowder Incident (or Gunpowder Affair) was a conflict early in the American Revolutionary War between Lord Dunmore, the Royal Governor of colonial Virginia, and militia led by Patrick Henry. On April 20, 1775, a day after the Battle of Lexington and Concord, Lord Dunmore attempted to remove the gunpowder from the magazine in Williamsburg, Virginia to a British ship.

http://en.wikipedia.org/wiki/Gunpowder_Incident