Here's the 'back story' on that lighter:
Beginning in 1939, World War II had a profound effect on Zippo. Upon America’s entry into the war, Zippo ceased production of lighters for consumer markets and dedicated all manufacturing and sales to the U.S. military.
However, all the grade one steel and brass was needed for the machinery of war, so Zippo Company had to use what was available, a secondary grade of steel for their production, instead. As for chrome or nickel: it was impossible to obtain to use for plating the steel cases. By early 1942 Zippo lighters made with this secondary quality steel started to corrode from humidity.
Born out of necessity in order to keep high quality standards, the cases were coated with a heavy black paint and baked for curing what resulted in a crinkly surface stucture, later on know as "black crackle finish", circa mid-1942.
The fact that millions of American military personnel carried the Zippo lighter into battle was a significant catalyst in establishing Zippo as an icon of America throughout the world. Supplying the military market resulted in full production for the plant. This enabled Zippo to be strong financially and made it a viable company.
(By the way, as an aside, date codes weren't stamped on the bottom of Zippo cases until the mid-1950's.)
Cobra 6 Actual