There's a coda to the Hindenburg tale to do with helium that I couldn't fit in: After the Hindenburg crash, Eckener vowed never to use hydrogen on a commercial airship ever again, and therefore didn't want to use hydrogen on the LZ 130 Graf Zeppelin. He pleaded, in person, with Roosevelt to allow helium exports to them as long as it was going to be for peaceful purposes, and Roosevelt eventually agreed.
However, following the Anschluss of Austria, the Secretary of State blocked the helium export and Eckener had to fall back to using hydrogen on the Graf Zeppelin. He forbade it from carrying commercial passengers, so its flights were only ever for publicity and propaganda, and was used for radio surveillance by the Nazis before being scrapped in 1940.