Earlier quoted context omitted.
Ok. X declares war on Y. Twitter takes it down so Y never sees it. Are they at war?
> X declares war on Y. [...] > Are they at war? Yes. Moreover, it doesn't matter, as no one declares war before initiating hostilities anymore; since aggression has been uniformly understood to be a crime, the only legitimate reason for waging war is is immediate, including imminent, national or collective self-defense (including, in the latter, implementation of UNSC resolutions pertaining to maintenance of peace an…
Now in an alternate universe where Germany didn't realise it was at war if it invaded Poland, so it never invaded France. Fast forward X years on, and France wants to sign a peace treaty (because it's embarrassing being in the EU but at war with a fellow member, and makes Schengen complicated), but Germany doesn't see the need because they aren't at war. Can France unilaterally declare peace? Is Germany at war? (I suppose theres a legal and real world answer to this)
I'm reminded of an urban legend, where Berwick on Tweed wasn't included in the peace treaty concluding the Crimean war, therefore still technically at war with Russia [1]. In all the tellings, a second treaty has had to be signed to end the war, which suggests both parties need to agree.
[1] http://www.berwickfriends.org.uk/history/berwicks-war-with-r...