In Hancock's story, one can see the ancestors of Swayze and the Wolverines in Bert Howard and the volunteer cadets of Gridley High School, who heroically defend New England from German invaders:
"My, those boys are tireless, and there's some fine soldier stuff in them," murmured Lieutenant Greg Holmes, an hour later, as he watched the drill. "There ought to be good stuff in them," returned Prescott. "Back in 1916 there was a wave of preparedness excitement swept this country, and a lot of high school boys everywhere were drilled enthusiastically. Then, bit by bit, the interest began to die out, and to-day we have comparatively few high schools were real soldiering is taught. But in Gridley the enthusiasm never died out."
Uncle Sam's Boys at the Battle of Boston was just the first part of Hancock's series depicting a war with German invaders rampaging across the United States; later stories included In the Battle for New York and At the Defense of Pittsburgh. On the eve of World War I, this didn't seem like a particularly far-fetched scenario. After all, it was a telegram suggesting a German-Mexican plan to invade the United States from the south that helped push American into the war.
The very real carnage of World War I, however, largely put an end to the fanciful genre, according to Clarke. Invasion stories never really recovered in popularity in the post-World War I period. In the interwar period, future-war fiction took a darker turn, with totalitarian dystopias and tales of poisonous gas clouds seeming to anticipate the rise of fascism and the carnage of Hiroshima, though there were still occasional invasion tales being produced, such as the dark 1929 novel Red Napoleon, which depicts a communist takeover of the United States. During the Cold War, books and films depicting a Soviet military invasion of the West were far less common than books and films like On the Beach and Dr. Strangelove depicting the threat of nuclear war, or The Manchurian Candidate, telling of undercover Communist subversion. When fighting did take place in America, the culprits were more likely to be extraterrestrials than real-world adversaries.
It's fair to say that the development of the atom bomb sounded the death knell for invasion literature. Fulda Gap aside, it has been clear that World War III would likely end in nuclear disaster rather than armies streaming across the borders of industrialized nations. And since the end of the Cold War, movies like The Siege and television series like 24 and Homeland have reflected anxieties over the potential of a terrorist attack on U.S. soil -- but there's little fear, in either military planning or popular fiction, of battle lines being drawn on U.S. soil.
Which brings us back to Red Dawn. Even at the time the original film was released, the scenario was pretty far-fetched. "Those who consider the events set forth in 'Red Dawn' to be probable are no more apt to find the movie credible than those who regard them as ludicrous," Janet Maslin wrote in her review for the New York Times. Books and movies from the same era, such as John Hackett's The Third World War: The Untold Story and Tom Clancy's The Hunt for Red October warned of catastrophic nuclear military confrontation with the Soviet Union, but they stopped well short of depicting fighting on U.S. soil. Red Dawn feels like such a bizarre outlier because, for the past 70 years or so, Americans have felt fairly confident that whatever threats they face, an enemy occupation is pretty low on the list. (Notable exceptions to the rule are video games like the Call of Duty series, which have allowed players to battle Russian baddies on the American homeland.)
Of course, as Clarke points out, the alarmist authors of the late 19th and early 20th century were strikingly bad at imagining what "future war" would look like. Rather than decisive Battle of Dorking-style routs, the modern military technology that was just over the horizon resulted in the grueling, brutal stalemate of trench warfare. He ends his history by noting that "This fiction has an almost unbroken record of failing to forecast the true course of future wars. The Germans never invaded the British Isles; and the French did not conquer Germany. When the long-expected war came in 1914, it turned out to be very different from the swift campaigns and decisive naval actions described in the tales of the ‘The Next Great War.'"
In other words, it's easy to laugh at Red Dawn. But just because Hollywood has, for the most part, decided that terrorists, hackers, spies, and nukes are the real threats we should be worried about doesn't mean we have any real idea of what the next war will bring.