Submarines as "The Silent Service" - Origin of name?

Factual Questions
1

I always thought it was because they operated under the sea and were stealthy and “silent” in operation. I was just watching the History Channel an it says it’s because they had a very strict code of silence about their operations during WWII and the press called them the “Silent Service” because of this.

Is the History Channel correct?

2

The term was older than that. The OED cites

This is not the only pre-WWII cite.

I think the US press may have picked it up, but didn’t invent it just for the subs.