Americans aren’t supposed to be interested in history. In the Twitter age, they aren’t supposed to have a long attention span. Americans are politically divided and don’t want to immerse themselves in a period of time when they were even more politically divided.

Ken Burns and Lynn Novick, in their 18-hour, 10-episode miniseries “The Vietnam War,” blew up each of these bits of conventional wisdom in fashioning an engrossing, horrifying and edifying look back at the Vietnam War. The documentary examines the war not simply from one or two American perspectives but from every conceivable angle — North Vietnamese, South Vietnamese, American soldier, American politician, American protester, American Gold Star mother, etc. The resulting documentary emotionally overwhelms the viewer at times but also provokes serious reflection. What defines patriotism? How does a democracy react when its leaders lie? How do presidents wrestle with the errors of their predecessors? How should the United States address failure?

The level of detail and meticulous research reflected on the screen distinguishes their work from the sea of dumbed-down news and superficial punditry we have grown accustomed to viewing. The filmmakers demonstrate that objective, voluminous research can unearth irrefutable data, from which people can draw starkly different conclusions.

If you begin watching with one perspective, you may change two or three times; if you’re not quite sure how you feel at the beginning, you may end up with a more profound sense of why that is entirely appropriate. Polarized times operate in the false world of moral certitude; recognizing ambiguity and contradiction can be freeing. But make no mistake — unlike with Burns’s prior film on the Civil War or the Burns-Novick miniseries on World War II, no happy endings nor silver linings offer viewers consolation for making the long trek through painful history.

You do, however, come away with deep respect for the fighting men who were so badly served by political and military leaders. The “greatest generation,” as one interviewee in the film acknowledged, is a crock; we had soldiers, sailors, airmen and Marines in Vietnam every bit as brave, daring, loyal and resourceful as their fathers, many of whom served in World War II. And for the record, we are not great because we always win, but because we are capable of self-reflection, remorse and reaffirmation of our values. The film also reminds us that democracies require a free press, healthy skepticism and active citizens.

Patriotism manifests itself in each episode both in service and in opposition. Protest, like all human activity, reveals both high-mindedness and selfishness. We are reminded that sincerity exists on both sides of a confusing, complicated issue.

In such a divisive, infuriating time as ours, a deep dive into another era provides welcome perspective. The country in 2017 is not the most divided America has ever been; Donald Trump is not the first president to engage in bald-faced lying (although in quantity and lunacy, Trump surely must lead the pack).

The amount of information Burns and Novick convey is stunning, with virtually no fluff or filler. An excruciatingly long, heartbreaking war deserves a film this long. (Viewers may be tempted to say, “It’s only 1965, and already it’s a quagmire! How can there be 10 more hours — and 10 more years of the war — left to go?)

For all this, we can say, well done, Mr. Burns and Ms. Novick — and thank you.