It was the end of innocence, the end of a particular world order and the end, more or less, of the time when “classical music,” as many people think of it, was written. World War I ended 100 years ago Sunday. And although the United States, which entered the conflict late in the game, has not made too much of this anniversary — compared with the intense focus around the 150th anniversary of the Civil War a few years ago — the music world is presenting legion Armistice Day concerts.

This includes some of the most significant Washington-area offerings of the season. This weekend, the Washington National Opera is opening “Silent Night,” Kevin Puts’s Pulitzer Prize-winning adaptation of the 2005 film “Joyeux Noel,” about the Christmas Truce of 1914, when soldiers in the trenches laid down their arms and sang carols together for a night before resuming shooting at each other. The National Symphony Orchestra will present Benjamin Britten’s “War Requiem” this month, written to commemorate the end of the Second World War, but setting poems by Wilfred Owen about the first.

On Monday, baritone John Brancy and pianist Peter Dugan return with a program called “Armistice: The Journey Home,” a follow-up to the 2014 program “A Silent Night,” also based on the Christmas Truce, which they first offered at Vocal Arts DC and have since performed around the world. This weekend, the New Orchestra of Washington (NOW) presents an Armistice Day commemoration with the Washington Master Chorale that includes a world premiere by Joseph Turrin; last month, the Cathedral Choral Society offered the premiere of a massive Requiem that the composer Alexander Kastalsky wrote in 1918 to commemorate the millions of fallen soldiers. And that’s only a sampling of the programs offered by the Thirteen, Choralis and many others.

Classical music loves anniversaries — because, more than any other branch of the arts, it’s focused on looking at an increasingly distant past. Classical music comes into its own at times of commemoration and mourning: Even the mass audience tends to embrace classical music at a funeral. And classical music, as it’s commonly thought of today, was mostly written in Europe before World War I ended — in the part of the world that was most deeply affected by the devastating changes of the war, which took place as classical music was already going through an upheaval. (Stravinsky’s “Rite of Spring,” that 20th-century watershed, had its premiere in 1913, a year before war broke out.)

Today, when classical music is eager to reassert its relevance to the world at large, this kind of historical presentation appeals to presenters. The question is whether these Armistice observances actually prove classical music’s relevance or simply serve to wrap history in a PBS soundtrack of nostalgia.

One argument for World War I commemorations is the vast literature of World War I music. In 1914, when the war began, classical music was a far more popular idiom than it is today. The artists and musicians who were affected by the war expressed their thoughts in symphonies and piano works rather than in protest songs. Today, the pianist Dugan says, “because we’re not dealing with the draft, we don’t have as much of a sense anymore of an army that’s made up of writers and composers and musicians. That makes for a very different feel in terms of the kind of art that’s being produced.” And commemorative music at the time was far more likely to have traction than it is today, when a piece such as “On the Transmigration of Souls,” John Adams’s 2002 memorial to the 9/11 attacks, can win the Pulitzer Prize without attracting much popular attention.

Brancy and Dugan’s 2014 “Silent Night” program focused on composers who had seen military action, George Butterworth and Carl Orff among them. NOW’s program this weekend, too, includes commemorations from Maurice Ravel, who drove a truck in the war and dedicated the movements of his famous “Le tombeau de Couperin” to friends who died in World War I; and Gustav Holst, who was rejected as unfit for military service and who wrote his “Ode to Death” in memory of friends who had died. The City Choir of Washington offers works by Gerald Finzi, who lost three siblings, and Ralph Vaughan Williams, who saw action himself.

But to be truly relevant in today’s market, many people feel you need new work, and commissioning new compositions about specific historic events is never easy. All too often, you end up with something portentous and stilted, a knockoff of Copland’s “Lincoln Portrait” — such as Peter Lieberson’s “Remembering JFK (An American Elegy),” commissioned by the NSO and premiered in 2011, which didn’t even have the modest half-life I predicted for it at the time as a ceremonial catchall. If you’re writing music about World War I, do you have an imperative to make music that evokes the early 20th century?

Alejandro Hernandez-Valdez, artistic director of NOW, is happy to program Radiohead on his concert: “Harry Patch (in memory of)” was inspired by a radio interview with the last living World War I combat veteran of the trenches, who died in 2009 at age 111. (The song was orchestrated by Radiohead member-cum-classical composer, Johnny Greenwood.) But when it came to selecting a composer for the co-commission, there was some discussion before Turrin was selected, to make sure they found a musical voice that fit. (The piece, called “And Crimson Roses Once Again Be Fair,” is set to poetry by World War I-era writers.) “He has the right kind of sound,” Hernandez-Valdez said. “He writes in a very lyrical way, but definitely contemporary.”

By the same token, Puts, the “Silent Night” composer, is very much a tonalist, writing music with a cinematic quality. For this opera, however, the historical setting gave a dramatic rather than a musical impetus; he explicitly opted not to work historical music references into his score, even writing new Christmas carols rather than using familiar ones. It’s an interesting decision, given that the opera is so imbued with a sense of time and place that it would be virtually impossible to update to any other historical period. You can make a case for “Rigoletto” in Mafia-era New York, but it’s hard to pretend that this kind of cease-fire, so innocent and naive, could have happened in Vietnam or Iraq.

There is, of course, nothing wrong with only using music of the past; programmers do it all the time. And the challenge is, in microcosm, the same one that faces the field as a whole: How do you present the past in ways that make it come to life?

For Brancy and Dugan, the answer proved to be a new model of song recital — “reinventing the way a program is structured,” Dugan said, “where all of the individual songs and elements combine to create one theme, that often resonates with areas outside of music.” The pair will record the new project for release early next year, after an exhaustive tour — eight cities in 11 days, they calculated last week — that demonstrates proof of concept, taking them from their Alice Tully Hall debut to a performance at the U.S. Military Academy at West Point. Since their first concert, they have been sponsored by the leading World War I commemorative organizations in the United States, Britain, and France. Monday’s concert is co-sponsored by the General Delegation of the Government of Flanders to the United States.

This kind of extramusical buy-in is a sign that a program has meaningfully connected with its subject: making people confront and think about World War I rather than simply offering a couple of hours of historicized reverie about an event that no longer looms large in the popular imagination. Indeed, all World War I concerts should be trying to connect with the historical realities of the time, rather than retreating into the wistful, nostalgic classical music trope: mourning the closing of a cultural door on the 19th century — a door that some purists are still fighting to keep open.

A few noteworthy World War I commemorations in the Washington area: “Silent Night” runs at the Washington National Opera through Nov. 25. Gianandrea Noseda will lead the NSO and the Choral Arts Society in Britten’s War Requiem from Nov. 29 to Dec.1. John Brancy and Peter Dugan will present “Armistice: The Journey Home” at Vocal Arts DC on Monday. The New Orchestra of Washington’s “End of the War to End All Wars” concert, which was performed Saturday night, will repeat in New York City on Sunday. The City Choir of Washington offers “A Farewell to Arms” on Sunday. The Washington Chorus presents the Brahms Requiem and Britten’s Ballad of Heroes in its Armistice commemoration Nov. 18. The ensemble Tapestry presents an Armistice Day commemoration at the National Gallery on Sunday.