Count Ferdinand von Zeppelin's project was one of many designs for rigid airships, but its success was so spectacular that the word became a casual term for all similar aircraft. Rigid airships became commercially available in late 19th century, and dominated air travel for 40 years. Count Zeppelin's airship was successfully tested in 1900, and soon became an important transport vehicle: the Luftschiffbau Zeppelin airline carried tens of thousands of passengers in the span of just a few years. In the WW I, German rigid airships were extensively used in scouting and bombardment, especially in England. Other world powers were seriously lagging behind Germany in rigid airship design, but a few Zeppelin-type units were in use in the USA and France. It was the famous Hindenburg disaster which ended the age of Zeppelin, as the air navies around the world moved solely to the heavier-than-air aircraft designs.