Toward the end of World War II . . .
Dresden was horrible, but what a bunch of propagandist tripe by whoever that author is.
and possessing no military value
Of course cities have military value, especially ones that are transportation nexuses.
A gentlemen's agreement seemed to prevail, designating Dresden an "open city."
So allied personnel could go there and hang out in some cafes and chat with the locals? Maybe the author means, no, they couldn't do that, but they could "hang out" and "chat".
Approximately 500.000 . . .
Or, as pointed out, maybe 1/20th of that amount.
Little did those refugees retreating from the Red terror imagine that they were about to die in a horror worse than anything Stalin could devise.
The author apparently has either read almost nothing about Stalin or is just lying.