The New Student's Reference Work/Sealed Orders

Seal′ed Orders are orders which are delivered to the commanding officer of a ship or squadron, sealed and only to be opened when at sea. The commanding officer of a ship or squadron is sent to sea under sealed orders when sailing on any secret service, to prevent the destination and object of the expedition from becoming known. The commander, equally with all under him, is ignorant of where he is to sail or what he is to do until the seal is broken.