have performed sufficiently to interest the German Army, who opted to purchase and operate it as the Z I until 1913. Even so, the German Army observed that they required an airship that would be capable of flying for 24 hours. As this was beyond the capability of LZ 3, it was decided to design and construct a larger craft, LZ 4. This was 136 m (446 ft) long, 12.95 m (42 ft 6 in) in diameter and powered by two Daimler engines delivering a total of 156 kW (210 hp). LZ 4 first flew on 20 June 1908, and on 1 July made a spectacular 12 hour cross-country flight during which it was flown over Switzerland to Zürich and then back to Lake Constance. The 24-hour trial was started on 4 August, but was interrupted by the failure of one of the engines. It was moored near Echterdingen in order to make repairs but a storm arose, causing it to break away from its moorings, after which it was blown into some trees and caught fire. The disaster took place in front of an estimated 40 to 50 thousand spectators, and produced an extraordinary wave of nationalistic support for von Zeppelin's work. Unsolicited donations from the public poured in: enough had been received within 24 hours to rebuild the airship, and the eventual total was over 6 million marks were donated, finally giving Count Zeppelin a sound financial base for his experiments. Seven zeppelins were operated by DELAG, the first airline in the world. DELAG was founded at the suggestion of Alfred Colsman, the business manager of Zeppelin Luftschiffbau, seeking to capitalise on the German public's enthusiastic interest in the zeppelin by permitting them onboard passenger-carrying airships as a commercial venture; von Zeppelin distanced himself from this commercialisation, reportedly regarding such efforts to have been a vulgar tradesman's enterprise. Commencing such flights in 1910, DELAG was initially limited to offering pleasure cruises in the vicinity of the existing zeppelin bases. DELAG soon received more capable zeppelins, such as the LZ 10 Schwaben, which would carry a total of 1,553 paying passengers during its career, which involved not only pleasure flights but a number of long-distance flights to destinations such as Frankfurt, Düsseldorf, and Berlin. The company's airships were also used by the Imperial German Navy for crew training, with the Navy crews operating passenger flights. By July 1914, one