The most straightforward theory for Western Rome's collapse pins the fall on a string of military losses sustained against outside forces. Rome had tangled with Germanic tribes for centuries, but by the 300s “barbarian” groups like the Goths had encroached beyond the Empire's borders.
No the Declaration of Independence was not intended to be a formal declaration of war since "<span>There was no need to declare war, as this power had yet to be established" and because it was implied. </span>