When Giuseppe Verdi wrote his Requiem he was something of an institution in Italy: the premier opera composer of his age and a strong advocate of national pride and culture.

His most recent opera, Aida, was a paean to love and country, replete with unmatched theatrical pageantry. When Italy’s other big-name composer, Giacomo Rossini, died in 1868, Verdi and others wanted to pay him tribute with a Requiem Mass (Verdi’s contribution was the “Libera me”), but the production never came off.

When Alessandro Manzoni, author of the important novel “The Betrothed” and unifier of the Italian language and spirit, died in 1873, Verdi decided to complete a Requiem in honor of his hero. What he produced is a masterpiece of the concert stage, an enormous work for choir, four vocal soloists and orchestra that melds the choral mass and opera styles.

At the heart of the work is profound human anxiety and longing — fear of death and hope for eternal life. These eternal sentiments, so magnificently expressed, are all the more extraordinary coming from a man who had no use for the Catholic Church and probably wasn’t religious. But Verdi’s combined humanism and patriotism fueled one of the most inspired musical works ever created.

And Saturday night, the Charleston Symphony Orchestra and Chorus, bolstered by the College of Charleston Concert Choir, joined by four up-and-coming singers and led by guest conductor Maximiano Valdes, offered up a moving and spirited rendering of the Requiem.

It was an ambitious performance with some symbolic significance. Not very long ago Charleston nearly lost its symphony orchestra. It did lose its musical maestro, David Stahl, who died of cancer in 2010, before he had a chance to revisit Verdi’s Requiem (one of his favorite works) with his beloved orchestra.

Saturday at the Sottile Theatre, then, was something of a minor miracle, a musical restoration completed, a clear indication that the symphony provides Charleston with something essential and fundamental: an expression of itself.

I confess I was nervous for the musicians. This is a very difficult piece. The quiet passages are meant to be extremely quiet; the loud parts are meant to be fortissimo, intensified with blaring brass and pounding bass drum. Singing it requires control, lots and lots of stamina, guts and excellent technique.

The performance was not perfect. Some of the movements, especially in the middle of the 90-minute-long piece, didn’t quite gel. The disparate parts — orchestra, chorus, soloists — each did fine, but sometimes the Requiem lacked a certain collective intensity and hush, a uniform sense of phrasing and expression across the overflowing stage.

It began with a solemn, delicate plea: “Grant them eternal rest, Lord, and may perpetual light shine upon them.” The melody is carried by the instruments; the chorus intones their segmented accompaniment: “Hear my prayer, unto thee all flesh shall come.”

And then the action starts, first with the solo singers each taking a turn with the “Kyrie eleison” (“Lord, have mercy on us”), and with the Earth-shattering “Dies irae” (“Day of wrath”). This is the Last Judgment, and the full chorus gave it everything it had. Valdes moved it along at a dramatic clip. It was hair-raising, scary, exciting, other-worldly indeed.

A sequence followed that showcased the soloists. Bass Adam Cioffari, a young singer with a warm, flexible tone and strong middle range, led off with Verdi’s lumbering version of Death. Tenor Harold Meers offered a clarion sound and terrific aria-like “Ingemisco.” Mezzo-soprano Cynthia Hanna displayed an impressive range and affecting chest voice, though her vibrato sometimes obscured her intonation. Soprano Jasmina Halimic sang convincingly with a lush and lovely tone, except at the top end of her range where some notes seemed a bit pinched.

I surely didn’t envy Halimic; the soprano part is the lynchpin of the whole piece. This is Verdi at his lyrical and dramatic best. The part demands intense discipline, musicianship, technique and endurance. Anyone familiar with this demanding piece waits impatiently for the “Requiem aeternam” and its quadruple-piano high B-flat.

As Halimic approached this famous note, she seemed to lose some steam, sagging under the pitch. And when she got there, it was a little rough and clipped.

The soloists generally were very good, but when singing together they didn’t always blend well or assert the tonality successfully.

The chorus, instead, was spot-on, well prepared by Rob Taylor and well led by Valdes. The orchestra, too, sounded great, despite some balance issues (a neighboring spectator thought the players were a little too loud at times, but I loved the intensity of the sound in the Sottile).

Valdes’ overall vision was evident, and his command of the music, and of the many musicians on stage, was admirable. That his vision was not entirely realized to its fullest potential was no significant loss, for what was realized was an exciting and memorable night of great music-making.