V For Victory "Serve In Silence" Label On Cover

Can anyone tell me what "Serve in Silence" refers to? When I bought the cover I though it was a stick-on label, but it is printed on the envelope. It apparently is the space for a return address, but I have never seen the "Serve in Silence" phrase before.

Thanks.

DonSellos

See: https://en.wikipedia.org/wiki/Ameri...World_War_II and the section on "Careless Talk."

Oakland CA was a major military for the war effort as was the entire SF Bay Area.

Edit to add this poster image:

Another philatelic item along the lines of "Loose lips sink ships" ...
By coincidence both of these meters are dated the day before D-Day.

Thank you parcelpostguy and John Becker. I appreciate the responses and the links/scans. If I were younger, I would collect WW II patriotics. So many interesting items.

DonSellos

Camp Kohler was located in the northeast corner of unincorporated Sacramento County, California, United States, until it was destroyed by a fire in 1947.Initially a camp for migrant farm workers, it became the Sacramento Assembly Center a temporary detention center for interned Japanese Americans in 1942. The site is one of 12 California assembly centers that share designation as California Historical Landmark No. 934. From 1943 to 1945 the camp was a training center for US World War II forces.

There are many variations. Here is a simple one.