The Past
The Past
[Cueball and Black Hat talking.] Cueball: Well, you know what they say. The past is a foreign country- Black Hat: -With an outdated military and huge oil reserves! Black Hat: Hmmm...

"The past is a foreign country, they do things differently there" is the opening line of " The Go-Between ", a novel by Leslie Poles Hartley (1895–1972), published in London in 1953. Black Hat notes that a country's past military tends to be less advanced than its current one, and that countries in the past had larger oil reserves as they had consumed less oil then.
If a country from the past existed in its old state today, other countries would likely leap at the opportunity to exploit its oil reserves.
Or: Black Hat could be considering sending the modern troops of a country from today back in time to rob the oil from the countries in the past. It could be profitable to invent a time machine for just that.
"Mozart in Mirrorshades" is a short story by Bruce Sterling and Lewis Shiner, which features the use of time travel to exploit earlier eras' natural resources.
Also, in the Hitchhiker's Guide to the Galaxy series, time has been exploited to use as energy. They say: "The Past is like a foreign country. They do things exactly the same there."
The "If history has taught us anything" phrase is used to start several quotes:
"If history has taught us anything, Arthur muses, it is that men with mustaches must never achieve positions of power." - Tom Rachman, The Imperfectionists "If anything in this life is certain, if history has taught us anything, it is that you can kill anyone." - Michael Corleone, The Godfather
The title text starts by fitting the usual pattern of this phrase, but in the second half humorously subverts it. It extends the "past as a foreign country" metaphor by implying that lessons learned from history can count as military intelligence to use against it.
A more recent movie, Christopher Nolan's Tenet (film) , also deals with destroying the past.
[Cueball and Black Hat talking.] Cueball: Well, you know what they say. The past is a foreign country- Black Hat: -With an outdated military and huge oil reserves! Black Hat: Hmmm...
