Demise
Following the Hindenburg disaster in 1937, Germany grounded its airship fleet with the intention of replacing their hydrogen gas with non-flammable helium. By this time, however, Europe was well on the path to World War II, and the United States, the only country with substantial helium reserves, refused to sell the necessary gas. International travel was crippled during the war, and fixed-wing heavier-than-air aircraft, able to fly much faster than rigid airships, soon became the favored method of international air travel.
Read more about this topic: Rigid Airship