Privateers were captains of merchant ships legally sanctioned to attack and capture ships of enemy nations In war American privateers played a major role, as armed merchant ships sailing from American ports attacked, seized, or destroyed a great many British merchant ships. Privateers or Merchant Mariners help win the Revolutionary War. To add to this, they issued Letters of Marque to privately owned, armed merchant ships and Commissions for privateers.
In the American Revolution, privateers transported arms, munitions and tropical products to the American continent. ... Following the American Revolution, many former privateers became captains on merchant ships, because without war, privateering was no longer needed on such a large scale.
The purpose of the Espionage Act was to prohibit interference with military operations, to ban support of U.S. enemies during wartime or to promote insubordination in the military.