DALLAS — It would be interesting to have been a fly on the wall when Steven Stucky learned that the Dallas Symphony wanted him to write an evening-length oratorio commemorating the centennial of President Johnson. “What in heaven’s name can I do with this?” he must have asked himself. The Dallas audience found out last Thursday evening when the first of four performances of “August 4, 1964” was given at the Meyerson Symphony Center by the Dallas Symphony, the Dallas Symphony Chorus, and four vocal soloists, all under the direction of the orchestra’s new conductor, Jaap van Zweden.

Mr. Stucky is an able composer whose orchestral work, “Rhapsodies” was given its American premiere on Friday, by the New York Philharmonic. With “August 4, 1964” he has produced a work that has its faults, but at least steers clear of sanctimoniousness. It is not a panegyric to Johnson but treats events from his presidency. It includes the involvement of librettist Gene Scheer (Picker’s “An American Tragedy”), whose legwork led to his realization that two signal events, each symbolizing a side of the Johnson presidency’s double-barreled legacy, took place on the same day. One was the discovery near Philadelphia, Miss., of the bodies of three civil rights workers. The other was the alleged attack on an American destroyer in the Gulf of Tonkin, which precipitated the Gulf of Tonkin Resolution that served as the legal basis of the Vietnam War.

An evenhanded portrait of Johnson emerges in “August 4, 1964,” one that more or less accords with the verdict of history in balancing his epochal achievements in the area of civil rights against the morass of Vietnam. (Johnson’s two daughters were reportedly invited to a performance but declined.) Johnson is indeed the focal point of “August 4, 1964,” but he is portrayed by one of four soloists who bear roughly equal responsibilities. Soprano and mezzo-soprano singers take the roles of the mothers of slain civil rights workers James Chaney and Andrew Goodman. Robert McNamara, who comes off here as a rather officious secretary of defense, is cast as a tenor, while Johnson himself is a baritone. The women have some poignant moments, such as Mrs. Chaney’s account of the murder of her grandfather following his refusal to sell his dairy farm to a white man. And tension builds as McNamara and Johnson grapple with how to deal with reports from Vietnam.

Mr. Scheer has said that “August 4, 1964” was not intended as a documentary, yet it feels like one much of the time, and an absorbing one at that. Too often, though, the music takes a backseat to the events that unfold during the 80-minute work, although Mr. Stucky does set up an interesting stylistic dichotomy, which struck me as rooted in traditions of American opera. The two mothers sing with a nostalgic lyricism that has an unmistakable hint of Americana, a little reminiscent of an opera by Douglas Moore or Carlisle Floyd, though harmonically more advanced. Exchanges between the men tend toward the idiom of John Adams’s so-called CNN operas, such as “Nixon in China,” particularly when McNamara sings with terse declamation against an accompaniment of bustling orchestral patterns; Johnson’s discourse, which often takes the form of heightened recitative, is more sober. The chorus also makes an important contribution, singing in a chordal style with piquant but rarely truly discordant harmonies. Mr. Stucky’s high-minded approach eschews quotation of familiar tunes and references to pop idioms.

But one kept waiting for the music to really take over. An instrumental piece called “Elegy” (the seventh of the work’s 12 sections) proved effective with its two-note “sighing” motive against the steady timpani beat, a motive that also occurs in music for the women. But, as one example, Mr. Stucky missed an opportunity for cogent musical commentary when the two strands of plot come together near the end, as the women realize that their sons “were not coming back,” thereby eliciting from the chorus the comment, “so many sons would not be coming back.” But instead of developing this into something extended and powerful, Mr. Stucky moves quickly on to Johnson’s speech to the nation about the Tonkin incident. I also have mixed emotions about the prominence Mr. Scheer gives to Stephen Spender’s poem “I think continually of those who were truly great” — a fine poem but one perhaps too difficult to parse in the context of a musical work.

In any case, Mr. van Zweden did a masterful job of shaping the piece and realizing its dramatic essence, backed by able contributions from orchestra and chorus. The soloists, dressed in 1960s fashions, were also fine. Laquita Mitchell and Kelley O’Connor excelled as the mothers, their voices occasionally blending in mellifluous bel canto. Vale Rideout brought out the nervous energy that here characterizes McNamara, and Robert Orth, a notable Nixon in the Adams opera, tellingly conveyed Johnson’s strengths and insecurities.

“August 4, 1964” has turned out to be more than just a pièce d’occasion. Mr. Stucky took on a challenging assignment and acquitted himself honorably. Whether it has a life outside Texas is something else again.