The smartest thing about Days of Future Past’s setting is its specificity. If it had been a few years earlier, the film would have returned to the 1960s like its previous entry, however it would have been a time of turmoil and unrest. A few years later and the “Me Generation” would have settled in for bellbottoms and disco dance floors. But 1973 was important because of a crucial, generation-defining event: it was the year of the Paris Peace Accords that brought about an official end to the Vietnam War, at least for papered power. Of course, one could ask Saigon and the troops stationed there what cold comfort that was two years later.

While never explicitly dwelled upon due to the movie’s ensemble nature—as well as the necessity for all non-DC superhero movies to be “uppers”—the Vietnam War casts a shadow over the entire film, much as it did in American life, particularly for the Boomer Generation that grew up reading Marvel Comics. When we left Charles Xavier during November 1962 in the last movie, McAvoy’s heroic leader was freshly paralyzed but hopeful for the future. The Cuban Missile Crisis ended with peace prevailing (in no small part thanks to the X-Men), and he and Moira McTaggert had just watched President John F. Kennedy’s rosy Thanksgiving Day address to the nation. Like a generation of real-life comic book writers and readers, Xavier was wounded but optimistic about the country’s destiny and a coming Civil Rights shift in the public consciousness.

Vietnam changed all that. By jumping to 1973, we skipped the real Civil Rights movement’s most intense boiling points in the late 1960s, which the social outcry for served as an inspiration in the X-Men comics, as well as many of the assassinations that defined the decade that also gave us the Beatles, Woodstock, and 2001: A Space Odyssey.

Yet Vietnam, due to its long-lasting and permanent scars on the American consciousness (particularly for those who lived through it) could not be overlooked. Perhaps, because it was so entrenched in the politics and social upheaval of that era, the war’s mere dwindling presence in early ’73 was enough to implicitly comment on those dense, painful issues the franchise skipped. After all, the damage from the most turbulent times are immediately felt simply by the mileage on Xavier’s face. If he is the personification of hope of human empathy, a fact that Stewart’s older variation all but concedes in this movie, then the fractured American zeitgeist from the intervening decade is immediately witnessed in young Xavier’s visceral misery; a psyche literally as broken as a country’s post-Woodstock funk that would define the materialism to come.

Just as the Cold War’s hottest moment made for an amusing Forrest Gump-styled backdrop in director Matthew Vaughn’s more swinging prequel, the peace treaty begrudgingly tolerated by U.S. President Richard Nixon (and executed by the perpetual pragmatist Henry Kissinger in no small part because he intended them to be the previous year’s “October Surprise”) defined the direction of events in this movie. For Days of Future Past, Lawrence’s Mystique leaves the jungles of Vientam, where a mutant platoon appears just as browbeaten as the rest of the enlisted young men, and heads straight to France in order to assassinate a war profiteer who has been illegally experimenting on mutants (Peter Dinklage). This assassination is the crux of the movie, because it sets off a chain reaction that will irrevocably lead to a war between mutants and the robotic Sentinels 50 years later, bringing about a manmade Armageddon.