This neat, green, 3-Cent, U.S. postal stationery envelope(U164; in very good-fine condition!)  was sent on March 13, 1878, from Annapolis, Maryland, to Lt. George W. Tyler, U.S. Navy, U.S.S. Plymouth, Norfolk, Virginia! The U.S.S. Plymouth, was a wooden-hulled, screw sloop-of-war commissioned in 1869, originally with the name, Kenosha. As the U.S. Naval Academy is in Annapolis, Maryland, the sender was likely someone in the U.S. Navy, as well! Interestingly, about 8 months prior to this mail being sent, the Plymouth sailed up the Potomac River in a show of force to those elements involved in the Great Railroad Strike of 1877 who might have threatened the safety of Washington D.C.! 

To continue, the fancy cancel from the Annapolis P.O. is decent, but indistinct. The CDS from the Annapolis P.O. is superb! 

Lastly, as for the condition of the envelope, it's in pretty good shape for something over 146 years old! It's very clean! The envelope has been reduced some at the left side where the envelope was opened by Lt. Tyler. The back flap is more than 90% complete, though. Noted imperfections aside, this is still a nifty example of mail to Lt. George H. Tyler, then serving in the U.S. Navy as an officer on the U.S.S. Plymouth!