Individual #third_battle_of_Ypres__Ypres__battle_of_Ypres  battle in World War I (1917); an Allied offensive which eventually failed because tanks bogged down in the waterlogged soil of Flanders; Germans introduced mustard gas which interfered with the Allied artillery
  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

No statement uses or specializes third_battle_of_Ypres; click here to add one.