Even a short breakdown in fuel supplies can have profound and dramatic  consequences  for  modern  economies.  This  paper explores  a  major  coal  shortage  in  Central  Europe  after  WWI which shook local societies for two years. The dissolution of the Habsburg  Empire  in  1918  provides  a  narrower  context  to  this study,  while  its  immediate  focus  lies  upon  the  development  of diplomatic  and  economic  relationships  between Czechoslovakia – a  WWI  victor and an  important coal exporter, and Hungary – a war losing state that was a net coal importer. This paper underlines the scale of the Hungarian reliance on fuels from Czechoslovakia, and suggests that this dependency was one of the chief arguments that motivated Budapest to cede Slovakia to  Prague’s  control  and,  more  generally,  to  accept  the  peace terms  proposed  at  the  Paris  conference.  It  is  safe  to  conclude that  economic  considerations  played  a  much  greater,  if  not dominant, role in the adoption of the peace treaty of Trianon of 1920  in  Hungary.  Overall,  the  paper  demonstrates  that  cross- border  energy  interdependence  substantially  influenced  diplo-matic relations in Central Europe immediately after WWI, privile-ging coal-exporting states over coal-importing states.