In early 1968, the Rev. Samuel Billy Kyles and another local minister beckoned the Rev. Dr. Martin Luther King Jr. to Memphis, Tenn., to demonstrate support for a strike by 1,300 black city sanitation workers. The strikers were demanding a minimum 10-cents-an-hour wage increase, workplace safeguards, and dignity. Their placards proclaimed, “I Am a Man.’’

King was reluctant at first; he was preoccupied with his Poor People’s Campaign. But he came to see that the Memphis strike converged with his national agenda for economic equality and social justice, so he accepted.

After King arrived, Father Kyles invited him to a home-cooked soul food dinner. Aware that King was perennially tardy, Father Kyles promised to pick him up promptly at 5 p.m. at the black-run Lorraine Motel, where King was staying, in Room 306. The date was April 4.

But when King later phoned the Kyles’ home to confirm the invitation, he learned that the dinner would actually be at 6. So when Father Kyles arrived around 5, King procrastinated.

He and a lieutenant, the Rev. Ralph David Abernathy, remained in the room with Father Kyles and enjoyed almost an hour of what Father Kyles later described as “preacher talk.’’

Before they left, Father Kyles picked out a necktie for King to wear to dinner.

When they finally emerged from the room, on a second-floor balcony, King was gunned down by a sniper from across the street.

Father Kyles died Tuesday, at 81, in a Memphis hospital. He was the last surviving witness to that motel-room conversation (Abernathy died in 1990) and, from the balcony, to King’s assassination.

“A lot of people claimed to have been on the balcony when Dr. King was shot down,’’ Father Kyles said.

Why had he been there? He often asked himself that question, he said.

“Over the years, God revealed to me why I was there,’’ he said. “Crucifixions have to have witnesses.’’

Father Kyles vividly recalled that evening in the documentary film “The Witness: From the Balcony of Room 306,’’ which was nominated for an Oscar in 2009, and in an interview for a publication put out by the Funders’ Network, a group of grant makers.

He remembered emerging from the room with King around 5:45. Hoping to keep the 6 p.m. dinner appointment, Father Kyles was trying to hurry him to a white Cadillac, borrowed from a local funeral home, that was waiting for them in the courtyard below.

“You’re not dressed for dinner,’’ King yelled down to another aide, the Rev. Jesse L. Jackson. From the courtyard, Jackson introduced King to Ben Branch, a local bandleader. (Andrew Young and Hosea Williams were also part of the entourage.)

King was talking to Branch over the balcony railing when a single rifle shot — “kuh-PIE-yah!’’ was how Father Kyles described the sound — reverberated from across the street.

“I thought I was having a nightmare, but the nightmare was that I was awake,’’ Father Kyles said. “And then we looked, and there was blood. So much blood.’’

King’s murder shocked the world, provoked riots in many of the nation’s cities, and devastated Memphis emotionally. On April 8, tens of thousands of demonstrators silently marched to honor King’s memory.

That May, caravans of protesters converged on Washington for King’s Poor People’s Campaign for economic justice.

“That’s where the witness comes in,’’ Father Kyles said. “Yes, you can kill the dreamer. Absolutely, you can kill the dreamer. But you cannot kill the dream.’’

Father Kyles was born in Shelby, Miss., a Delta town, on Sept. 26, 1934, to the Rev. Joseph Henry Kyles and the former Ludie Cameron. He was named for the prophet Samuel, but after his mother saw him baptizing neighborhood pets and memorializing dead birds, she began calling him Billy, after the evangelist Billy Sunday.

The family moved to Chicago when he was 6, and he attended Northern Seminary. He started preaching when he was 17 and singing even before that. (Aretha Franklin once said that her version of the gospel song “Never Grow Old’’ was inspired by Father Kyles’.)

When he decided to return to the South, his brothers scoffed.

“You’re in the promised land,’’ he recalled them saying. “Here you are going back to Egypt, to Memphis.’’

He settled in Memphis, a segregated city, in 1959 and became the founding pastor of Monumental Baptist Church. In perhaps a foreshadowing of King’s visit in 1968, he met with the civil rights leader Medgar Evers five years earlier at Evers’s Mississippi home shortly before Evers was murdered in his front yard.

Father Kyles became a central figure in Memphis’s struggle for civil rights. In 1961, his daughter Dwania was one of 13 black first-graders to integrate Memphis public schools. “We did not want to make the mistake that Little Rock had made and send high schoolers,’’ he said, referring to the hostile reaction to a similar integration effort in Arkansas in 1957 that compelled President Dwight D. Eisenhower to send in federal troops.

He was later arrested for refusing to sit in the back of a segregated city bus. Faced with the threat of a bus boycott, the city desegregated its buses in 1964.

Father Kyles was instrumental in the largely peaceful integration of restaurants and other public places in Memphis and the elimination of a system of runoff elections, which impeded minority candidates. He also formed a chapter of Jackson’s civil rights organization Operation PUSH (People United to Save Humanity) and was later a board member of the National Civil Rights Museum, established at the site of King’s assassination.

“He was a founding father of the New Memphis and the New South,’’ Jackson said at a tribute to Father Kyles this month at the church he led for 55 years until he retired in 2014.

In addition to his wife, the former Aurelia Kennedy, who confirmed his death, Father Kyles leaves their daughter, Epernay; four children from a previous marriage, to the former Gwendolyn Hart — his daughters Dwania and Drusheena and sons Dwain and Devin — and five grandchildren.

Father Kyles recalled that King had left a deep impression.

“I look at Martin’s picture, and he’s the only one who didn’t get old,’’ Father Kyles said. “But what a price to pay for not getting old.’’