sentences:  Significant oil fields were exploited in Alberta (Canada) from 1947.First offshore oil drilling at Oil Rocks (Neft Dashlari) in the Caspian Sea off Azerbaijan eventually resulted in a city built on pylons in 1949.Availability of oil and access to it, became of "cardinal importance" in military power before and after World War I, particularly for navies as they changed from coal, but also with the introduction of motor transport, tanks and airplanes.