For some people it was news that Wikidata supports dates. The question put to me was: "This Q130847 has geo coordinates but no date". As this refers to the battle of Verdun, I replied by adding the start and end date to the Wikidata item for the battle of Verdun.
One bit of good news is that MediaWiki does support the Islamic calendar, as a consequence the issue of using the calendar got a new dimension. I was also asked if other calendars like the Balinese calendar could be supported. In principle MediaWiki should support any calendar however, I would prefer to start with the support of calendars that MediaWiki supports in Wikidata.
The bug for support for the Islamic calendar in Wikidata was given the I18N label in Bugzilla. I hope that our language team will take an interest in supporting calendars in Wikidata
As it is fairly obvious that the battle of Verdun is a battle, I added "Instance of" "battle". When you look where battle links in Wikidata you will find many more battles that are linked to the concept of battle. I added a few more battles that I just happened to know.
When you look at the info-box for the battle of Verdun, you find many bits of information that we should be able to support in Wikidata. It would be cool when we can.