Zeppelin began working with balloons for human transport as an observer during the American Civil War. In 1891, he retired from the Prussian army to devote himself to building motor-driven airships. Zeppelin invented the first rigid airship in 1900, but the experiment exhausted his funds. Luckily, public opinion was so strongly in favor of his airship project that donations largely financed his future work. Whom did his granddaughter later threaten to sue for sullying her family’s name? Discuss