Les McCann, a musician who helped shape the “soul jazz” style of the 1960s with his earthy piano playing and singing and whose live recording of the antiwar anthem “Compared to What” became a musical touchstone of the era, died Dec. 29 at a hospital in Los Angeles. He was 88.

The cause was pneumonia, said Alan Abrahams, a record producer and McCann’s longtime manager and songwriting partner.

Largely self-taught on piano, McCann began his career as a leader of jazz trios, recording more than 30 albums during the 1960s. Along with saxophonist Julian “Cannonball” Adderley, organist Richard “Groove” Holmes and others, he was a major exponent of soul jazz, which combined the virtuosity of bebop-inspired jazz with the melodies and propulsive rhythms of Black gospel music and blues.

A popular performer in nightclubs and on television, McCann gained his greatest acclaim in 1969 with his performance of “Compared to What,” a politically charged protest song by Gene McDaniels that became a rhythm-and-blues hit at the height of the Vietnam War.

Soon afterward, McCann – a relentless musical explorer – began to experiment with electronic instruments during the emerging jazz fusion movement. His energetic, rhythmically complex style influenced later generations of hip-hop musicians, including Snoop Dogg, Dr. Dre and a Tribe Called Quest, acts that sampled McCann’s recordings in their own work.

Some of his initial devotees accused him of selling out and deserting his jazz roots. New Yorker jazz writer Whitney Balliett once called McCann “the pasha of soul-soap music.”

In a 1991 interview on “CBS Sunday Morning,” however, McCann said his musical inspiration always came from the same source: “It’s not the instruments. It’s me.”

During a career that lasted into his 80s, McCann wrote hundreds of songs and released more than 60 albums, yet his signature tune remained “Compared to What,” which he first recorded in 1966.

The song did not catch on until McCann decided to use it as his opening number during an appearance at the Montreux Jazz Festival in Switzerland on June 21, 1969. He and his trio – bassist Leroy Vinnegar and drummer Donald Dean – were joined by Eddie Harris on tenor saxophone and Benny Bailey on trumpet. There was no time for a rehearsal, and the horn players had never played with McCann before, but the resulting eight minutes of music became something of a happy accident of jazz.

McCann charged into “Compared to What,” pounding out a powerful rhythmic figure on piano as Dean kept pace on drums. Ripples of applause welled from the audience as McCann began to sing the mildly profane lyrics, which touched on sensitive social issues and were an undisguised indictment of the government and religion:

The President, he’s got his war

Folks don’t know just what it’s for

Nobody gives us rhyme or reason

Have one doubt, they call it treason

We’re chicken-feathers, all without one nut. God (expletive)!

Tryin’ to make it real, compared to what?

Spurred on by McCann and the rhythm section, Harris and Bailey played fiery improvised solos as the audience grew more impassioned, giving the group a thunderous ovation.

“Compared to What” was released on McCann’s “Swiss Movement” album, which included several other tunes – all of them instrumentals – performed at Montreux. The album topped Billboard magazine’s jazz chart and received a Grammy nomination, and “Compared to What” became a rhythm-and-blues hit, reportedly selling more than 1 million copies. Some radio stations refused to play the song because it included the word “abortion,” but it has since been recorded more than 250 times.

“I’ve never been a predictor of the future,” McCann told the Lexington (Ky.) Herald-Leader in 2008. “But I always knew we had a great song with ‘Compared to What.'”

Leslie Coleman McCann was born Sept. 23, 1935, in Lexington. His father was a custodian who enjoyed music and drawing. His mother, a homemaker, was an amateur singer who listened to opera on the radio.

McCann took a few piano lessons as a child, but he played drums and the sousaphone in his high school band. He also worked at a local theater, helping musicians unload their equipment in return for tickets to the performances.

After high school, he joined the Navy and won a talent contest as a singer, leading to an appearance on “The Ed Sullivan Show” in 1956. He didn’t begin playing the piano in earnest until he was 20 and heard a recording of pianist Erroll Garner performing the standard “Lullaby of Birdland” and was mesmerized.

“It happened when I was in the post exchange,” he told the Detroit Free Press. “I fainted right on the floor.”

By 1958, McCann had settled in Los Angeles, where he briefly studied acting while launching his musical career. He impressed visiting musicians, including trumpeter Miles Davis, with his dynamic, bluesy style and turned down an offer to join Adderley’s band, preferring to lead his own groups, which he called Les McCann Ltd.

He released his first albums in 1960 – “Les McCann Ltd. Plays the Truth” and “Les McCann Ltd. Plays the Shout.” Two years later, he and his group backed singer Lou Rawls on his debut recording, “Stormy Monday.” In the late 1960s, McCann discovered singer Roberta Flack at a Washington nightclub and arranged for her to make her first albums with the Atlantic label.

In 1971, McCann performed before 100,000 spectators in Ghana during a 14-hour concert that also featured Wilson Pickett, Santana and Ike & Tina Turner. He appeared with Rawls at the White House during Bill Clinton’s presidency and toured the world with groups that included, at various times, flutist Herbie Mann and guitarists Cornell Dupree and Gregg Allman.

McCann always traveled with cameras, taking pictures that he developed in a darkroom at his home in Los Angeles. In 2015, he published “Invitation to Openness,” a collection of his photographs of musicians, including Nina Simone, Aretha Franklin and John Coltrane.

McCann was predeceased by his wife, Charlotte, and a daughter. A complete list of survivors was not immediately available.

In the 1990s, McCann had a stroke that limited his playing for a time. He returned to full strength by 2002, when he released “Pump It Up,” which featured his vocals over hard-driving funk rhythm patterns.

When McCann toured France to promote the album, his manager, Abrahamson, recalled, a journalist asked why he would give up the aesthetic purity of jazz in favor of funk music and amplified electronic instruments.

“If you want to know why we did a funk album,” McCann said, “it’s in the first three letters: F-U-N.”