Late Roman empire represents a switch from the very decentralized (and very, very light) bureaucracy to a much more hands on approach that was highly influential.

Problem is, its very expensive, but it was better than going through the third century crisis again.

Japan was already very committed to extreme expansionist policies by this point with the invasions of China and French Indochina. More than that, Japan had already allied itself with the Axis, though somewhat loosely.

If the US wanted peace, they would have to essentially entirely abandoned Asia.

Oh no, he has very much earned his reputation as pseudohistorical hack with his terrible research methodology, heavy reliance on old, outdated, and often plain bad secondary sources without doing even basic checks. (For instance, are they even reading the maps they're working with?), and his blatant mischaracterization of the field and studies.

Of course, Graham's explanation for why anyone knowledgeable in the field immediately calls him out for his flagrant and basic mistakes is that they must be in cahoots instead of his "research" being terrible.

Is the comment that Samhain is a pagan tradition that somehow survived 400 years as pagan?

Halloween as we know it today generally seems to not have been part of early Christian celebrations, only really seem to be getting into swing the past couple hundred years.

Probably later and much more recent than the 9th century, at least in whatever guise we see it today. This goes for a lot of trying to back date modern traditions to things more than a thousand years ago.

There is kind of a period in the 19th century where many "folklorist" thought they could parse out pre-Christian traditions from their modern day practices and thus tease out over thousand year old beliefs and traditions, which is a bit dubious and as fraught with mistakes as it might sound.

Eh, I would be a little skeptical on celebration first mentioned in the 9th century as being influential on Christianity given that Christianity took hold in the 5th century.

It helps when your religion doesn't actually have any serious dietary restrictions.