what is the {start time} for {Belgrade} has {country} as {Territory of the Military Commander in Serbia} ?
When did Belgrade become the territory of  the military commander in Serbia?
SELECT ?value WHERE { wd:Q3711 p:P17 ?s . ?s ps:P17 wd:Q701914 . ?s pq:P580 ?value}
select distinct ?value  where {
?statement <http://www.w3.org/1999/02/22-rdf-syntax-ns#subject> <http://wikidata.dbpedia.org/resource/Q3711> .
?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/Q701914> .
?statement <http://www.wikidata.org/entity/P580> ?value. 
} 

At what time did Belgrade become a territory of the military commander in Serbia?