DELAG, acronym for Deutsche Luftschiffahrts-Aktiengesellschaft (German for "German Airship Travel Corporation"), was the world's first airline to use an aircraft in revenue service. It was founded on 16 November 1909 with government assistance and operated Zeppelin rigid airships manufactured by the Luftschiffbau Zeppelin Corporation. Its headquarters were located in Frankfurt, Germany.
Alfred Colsman served as the airline's first general director. Also involved in the early stages were Dr. Love and Dr. Franz Adickes, the mayor of Frankfurt. The founding capital amounted to three million Marks, of which the majority (Mk 2,600,000) came from the cities of Frankfurt and Düsseldorf. The remaining Mk 400,000 came in the form of the airships from the Zeppelin plant in Friedrichshafen.
Passenger service aboard the airship LZ 7 began in 1910 with routes from Frankfurt to Baden-Baden and Düsseldorf. This vessel, known as the Deutschland, was destroyed on 28 June 1910 (nine days after its maiden voyage) when it crashed into the Teutoburger forest. One year later, a steward was introduced aboard the new airship LZ 10 Schwaben and was responsible for the well-being of the passengers.
By 1913, DELAG had established a route network between Frankfurt, Düsseldorf, Baden-Oos, Berlin-Johannisthal, Gotha, Hamburg, Dresden and Leipzig. The outbreak of World War I prevented the planned expansion to other European capitals.
By July 1914, one month before the start of World War I, DELAG's Zeppelins had transported 34,028 passengers on 1,588 commercial flights; the fleet had flown 172,535 kilometres in 3,176 hours. 
Impact of World War I 
The airships LZ 11, LZ 13, and LZ 17 were pressed into service for the German Army. After the war, however, DELAG's LZ 120 "Bodensee" and LZ 121 "Nordstern" helped reconnect the cities of Europe. LZ 120 already flew between Friedrichshafen and Berlin-Staaken with a stopover in Munich, but both ships were surrendered as post-war reparations in 1921: LZ 120 went to Italy and was re-christened "Esperia", while LZ 121 became France's "Méditerranée" before it ever entered service for DELAG.
Transatlantic service 
In September 1928, DELAG began operating the successful rigid airship LZ 127 Graf Zeppelin, which made regular, nonstop, transatlantic flights possible before airplanes had flight ranges sufficient to cross the ocean in either direction without stopping. For DELAG's first transatlantic trip, Dr. Eckener commanded the Graf Zeppelin airship leaving Friedrichshafen, Germany, at 07:54 on October 11, 1928, arriving at Lakehurst Field, New Jersey, on October 15. In 1931, the airship Graf Zeppelin began offering regular scheduled passenger service between Germany and South America which continued until 1937. Over its career Graf Zeppelin crossed the South Atlantic 136 times. In 1936, the airship Hindenburg entered passenger service and successfully crossed the Atlantic 36 times before crashing at Lakehurst, New Jersey on May 6, 1937.
The Graf Zeppelin was the final airship employed by DELAG. In 1935, the successor to DELAG, the state-sponsored Deutsche Zeppelin-Reederei (DZR) was founded. Its fleet included the LZ 127 Graf Zeppelin, LZ 129 Hindenburg and LZ 130 Graf Zeppelin.
In 2001, a modern firm also by the name Deutsche Zeppelin Reederei was established as a subsidy of Zeppelin Luftschifftechnik GmbH (ZLT). It operates the Zeppelin NT07 Baden Wurttemberg airship on sightseeing flights around Germany.
Prior to World War I:
- LZ 6
- LZ 7 Deutschland
- LZ 8 Deutschland (replaced LZ 7)
- LZ 10 Schwaben
- LZ 11 Viktoria Luise
- LZ 13 Hansa
- LZ 17 Sachsen
Following World War I:
- "Delag" Encyclopædia Britannica (2009). Retrieved May 5, 2009.
- The Early Years of German Commercial Aviation
- Airships: A Zeppelin History Site
- Information about DELAG successor Deutsche Zeppelin-Reederei
- This article incorporates information from the German Wikipedia.