The concept of a unified Europe, which has materialised into the EU of today, was established in order to make the continent and its neighbourhood a safer place following the two World Wars. There is nothing to suggest that without unity these sorts of events cannot happen again.
It may appear quite rhetorical to affirm that Brexit would affect the EU project as a whole. Brexit is, however, something more than that.
Foreign and security policy will be one of the key issues in the lead up to the referendum on whether the UK should remain in or leave the EU on 23 June 2016.