@deborahh You're right that "jingoism" now applies to all nationalist military sloganeering. It's originally from the chorus of a popular 1878 British music-hall song:
We don't want to fight but by Jingo if we do,
We've got the ships, we've got the men, we've got the money too,
We've fought the Bear before, and while we're Britons true,
The Russians shall not have Constantinople
"By Jingo!" (for "By Jesus!) is older, but the song's use of it gives us the term.
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