Twain wrote this in his notebook after his story was rejected:
None but the dead have free speech.
None but the dead are permitted to speak truth.
In America -- as elsewhere -- free speech is confined to the dead.
The minority is always in the right.
When the country is drifting toward Philippine robber-raid henroost raid, do not shirk your duty, do not fail of loyalty, lest you win and deserve the reproach of being a "patriot."
The majority is always in the wrong.
Whenever you find that you are on the side of the majority, it is time to reform.
Eventually, in 1923, "The War Prayer" was published in a book, "Europe and Elsewhere". Here is an excerpt: