what is the {start time} for {Canton of Bern} has {country} as {Old Swiss Confederacy} ?
What date did the Old Swiss Confederacy add the Canton of Bern.
When did Canton of Bern join the Old Swiss Confederacy?
SELECT ?d WHERE { ?n property:country resource:Old_Swiss_Confederacy . resource:Bern property:country ?n . ?n property:start_time ?d }
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q11911> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#predicate> <http://www.wikidata.org/entity/P17> .
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#object> <http://wikidata.dbpedia.org/resource/Q435583> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

SELECT ?value WHERE { wd:Q11911 p:P17 ?s . ?s ps:P17 wd:Q435583 . ?s pq:P580 ?value}