#1) you CAN use 'the' with singular and pronouns. For example, you can say "The baby" OR "The babies"
#2) We sometimes DO use articles before the names of academic subjects. For example, if someone were to ask you what subject you are working on in independent study, you could reply with "The english" or "The math"
#3) We DO use 'the' when talking about popular things or places. For example, you could say "Grab THE phone"
The author seems to want to make the reader step back and ponder, maybe a bit out of fear as much as anything else. And he does so by using loaded words like " grave " Invasion " " premeditated " ect. ect.