KANSAS CITY, Mo. — April 6 marks the 100th anniversary of America’s entry into World War I, whose U.S. soldiers are commemorated by the city’s 217-foot Liberty Memorial tower.

But underneath this soaring monument is where things get interesting. It’s where you’ll find an amazing 50,000-square-foot bunker dug a little more than a decade ago to house the National World War I Museum, where more than 2 million people have visited since it opened in late 2006.

Inside its doors, a sky-lit, plexiglass-bottom bridge crosses over a display of 9,000 red silk poppies, harking back to the famous World War I poem that begins, “In Flanders fields the poppies blow ...”

Each flower represents 1,000 combatant deaths. That’s a total of 9 million lives, worldwide, not to mention the millions of civilians who perished in the 1914-18 conflict that was supposed to be the War to End All Wars.

As museum communications chief Mike Vietti notes, World War I was “messy and confused,” a story far more complex than U.S. “doughboy” soldiers going to help Britain and France defeat Kaiser Wilhelm’s German army.

The museum (www.theworldwar.org) circles the memorial tower’s below-ground base. Walk it counterclockwise to follow events chronologically.

The first of two semicircle galleries covers what led to the conflict and its horrendous trajectory prior to U.S. intervention. The second focuses on the American experience, the war’s end and the rancorous peace treaties that made World War II inevitable.

A small cinema is home to the introductory film “A World on the Edge,” setting the scene for what unfolds. Halfway through the museum, a widescreen theater with amphitheater seating shows a short movie that asks, “Should America Enter the War?” In the well between the front-row benches and the screen is a pause-inducing re-creation of no-man’s-land, featuring actual war wreckage from the museum collection.

Along the way, large and easy-to-understand maps and diagrams explain how various countries aligned and executed a technology-driven war that destroyed empires.

At interactive areas, you can hear recorded speeches, recollections and music of the time. Propaganda posters are scattered throughout; at one high-tech table, you can cannibalize parts of posters of different nations, create your own and email it to yourself. Elsewhere, stick your head through a diorama opening into a German trench and listen. Walk into a reproduction of a shell crater.

Larger exhibits include a French 6.4-ton Renault FT17 tank with its original wooden tread spokes and an engine a tad more powerful than that of a modern riding lawn mower.

Major battles, from the English Channel to the Russian steppes, all get their due. The war at sea, the Italian front and campaigns in East Africa, Turkey, the Middle East and elsewhere are addressed.

Glass cases are armed to the teeth with rifles, sidearms and the like, while other displays detail humanity through letters, among other things.

Early on, cases of extravagant combat uniforms abound — many looking more suitable for an operetta than the total war touched off by the 1914 assassination in Sarajevo of Archduke Franz Ferdinand, heir to the throne of the Austro-Hungarian Empire.

Much later, you see a German and American uniform both worn by Christian Nicolaisen, an ethnic Dane who was forced into the Imperial German Army. He deserted and moved to America, where he was drafted after the U.S. joined the fray.

Far luckier was a man named John Herbst, whose paperwork shows he was drafted in Kansas City on Nov. 11, 1918 — when the war officially ended — and was discharged the same day.

A worn and starving Germany agreed to an armistice on Nov. 11, 1918. Peace treaties were signed in the following months. President Woodrow Wilson’s war pledge to “make the world safe for democracy” was derailed by other victors’ calls for reparations and boundary changes.

The museum also highlights the civic drive to build the Liberty Memorial; the $2.5 million raised in two weeks funded the tower and two flanking halls that served as the museum until 2006. (Wear and tear and neglect over the years prompted a succession of fundraising efforts in Kansas City; a bond referendum and sales tax helped result in the modern museum.)

The epilogue section quotes eight people about what the war meant, from English writer H.G. Wells to a bitter, wounded, Austrian-born German soldier named Adolf Hitler.

Start to finish, the museum’s well-curated photography — whether a locket cameo or a wall-size image — is searing. Individuals, groups and masses, whether at home, going to war, dead on a battlefield or surviving in trenches, amplify the human experience and cost.

The visit ends where it began, at the bridge over the 9,000 artificial poppies. Represented among that number is Canadian Lt. Col. John McCrae, a physician and poet who died near the Western Front in early 1918. In following decades, his “In Flanders Fields” made the poppy a lapel memento worn on what is now called Veterans Day:

In Flanders fields the poppies blow

Between the crosses, row on row,

That mark our place; and in the sky

The larks, still bravely singing, fly

Scarce heard amid the guns below.

John Bordsen is a freelance writer.