Given the sound, one might assume that war had been declared. It would be a logical conclusion. Denmark is after all preparing for war at the start of this play. One might assume that Fortinbras has come to take over, not to report on his other wars. (I mean, he does sort of take over but only because no one is left in this royal court.)
This raises the question for me of who all those war preparations at the start were for. Is it support troops for Fortinbras’ campaign? Does Claudius do more for that war than just grant permission for Fortinbras to march through?
Also – it is very interesting that Norway and England greet each other with warlike noise – even though they both simply come with news.
And they arrive at the same moment?
Couldn’t they have arrived a little sooner and forestalled this little sword play?