The "Linen Card Era" of Post Cards was from 1930 to 1945. Most World War II Post Cards were printed on this linen type paper stock. Soldiers would send these mementos home as proof of "being there" in the case of attending one of the camps or forts depicted in the cards. They were an inexpensive (if not free) way to correspond with loved ones or friends back home or around the world.
The exact date of the establishment of the Norfolk Navy Yard is not known but it was started by the British prior to the Revolutionary War and named by them Gosport, the name by which it was known until after the War Between the States.