Individual #second_battle_of_Ypres__Ypres__battle_of_Ypres  battle in World War I (1915); Germans wanted to try chlorine (a toxic yellow gas) as a weapon and succeeded in taking considerable territory from the Allied salient
  instance of:  #pitched_battle
  part of:  #World_War_I__World_War___Great_War__First_World_War__War_to_End_War  a war between the Allies (Russia France British-Empire Italy US Japan Rumania Serbia Belgium Greece Portugal Montenegro) and the Central Powers (Germany Austria-Hungary Turkey Bulgaria) from 1914 to 1918
  part of:  #Belgium__Kingdom_of_Belgium__Belgique  a monarchy in northwestern Europe; headquarters for the European Common Market and for the North Atlantic Treaty Organization
     part of:  #Europe  the 2nd smallest continent (actually a vast peninsula of Eurasia); the British use `Europe' to refer to all of the continent except the British Isles
        part of:  #Eurasia  the land mass formed by the continents of Europe and Asia
           part of:  #eastern_hemisphere__easternhemisphere__orient  the hemisphere that includes Eurasia and Africa and Australia
           part of:  #northern_hemisphere  the hemisphere north of the equator

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