query: PREFIX wikibase: <http://wikiba.se/ontology#>
  PREFIX wd: <http://www.wikidata.org/entity/> 
  PREFIX wdt: <http://www.wikidata.org/prop/direct/>
  PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
  PREFIX p: <http://www.wikidata.org/prop/>
  PREFIX q: <http://www.wikidata.org/prop/qualifier/>
  PREFIX v: <http://www.wikidata.org/prop/statement/>
  
  SELECT
    ?war
    ?warLabel
  WHERE {
    ?war wdt:P31/wdt:P279* wd:Q198               .  # instance of: subclasses of War
    FILTER NOT EXISTS { ?war wdt:P580 ?startDate }    # without startDate
  
    SERVICE wikibase:label {
      bd:serviceParam wikibase:language "en" .
    }
   }