I found that Twain bit during a long web search for something I couldn't find: a satire on new weapons technology from the 1860s that is anthologized in The Sub-Treasury of American Humor. I can't find that book in my house yet either; the search continues. It's a lovely bit of writing and entirely appropriate today.
The whole search was sparked by this hilarious/horrible article on the return of the discredited, stupid, and entirely evil "Brilliant Pebbles" weapons project, part of the Reagan era Strategic Defense Initiative that was popularly known as the "Star Wars" system.
This is courtesy of Lowell Wood, our current living Strangelove. A disciple of Teller, he believed in every mad science approach to strategic defense: killer satellites, nuclear explosions in space, throwing rocks really fast at missiles, and X-ray lasers. The last one is a beauty: nuclear bombs in satellites would be detonated and their radiation focused into laser beams.
Wood's still at it. His entire career and ego are attached to the scheme.