Sinclair died Tuesday morning at Detroit Receiving Hospital of congestive heart failure following an illness, his publicist Matt Lee said.

Sinclair drew a 9 1/2-to-10-year prison sentence in 1969 from Detroit Recorder’s Court Judge Robert Colombo for giving two joints to undercover officers. He served 29 months but was released a few days after Lennon, Stevie Wonder, Bob Seger and others performed in front of 15,000 attendees at the University of Michigan’s Crisler Arena.

“They gave him 10 for two/What else can Judge Colombo do/We gotta set him free,” Lennon sang in “John Sinclair,” a song the ex-Beatle wrote that immortalized its subject.

Lennon and his wife, Yoko Ono, performed at the Dec. 10-11, 1971, “John Sinclair Freedom Rally,” held at the basketball arena in Ann Arbor. They took the stage after 3 a.m., about eight hours after the event got underway.

Earlier in the night, Sinclair’s wife, Leni, had called her imprisoned husband, and the conversation between the couple and their 4-year-old daughter, Sunny, was amplified for the crowd, who chanted “Free John!”

“I’m trying to get home. I want to be with you,” a sobbing Sinclair told the crowd that night, a Friday.

And he was by Monday.

At the time of Sinclair’s arrest, possession of marijuana was a felony, punishable by up to 10 years in prison. He was arrested in Detroit while living as a poet and activist who co-founded the White Panther Party. He received the maximum sentence.

The day before the concert, the Michigan Legislature voted to reduce to a misdemeanor the penalty for possession of small amounts of marijuana, punishable by up to a year in prison.

Because he already had served 2 1/2 years, Sinclair was released from prison three days after the concert.

“For me, it’s like coming into a whole different world from the one I left in 1969,” Sinclair wrote in “Guitar Army,” a collection of his writings that was published in the early 1970s.

Sinclair continued his advocacy for marijuana, helping to usher in Ann Arbor’s token $5 fine for pot possession and celebrating when his home state legalized recreational cannabis in 2018.

“I’m the pioneer. I was the first one in Michigan who said marijuana should be legal, and they said I was totally nuts,” he told the Detroit Free Press in 2019. “I’m proud to have played a part in this. I spent nearly three years in prison because of marijuana.”

Sinclair was born in Flint in 1941. His father worked for Buick for over four decades and his mother was a high school teacher who gave up her job to raise John and his two siblings. Sinclair grew up in Davison, a town not far from Flint, and graduated from the University of Michigan-Flint in 1964 with a degree in English Literature.

Over the next six-plus decades, Sinclair did a bit of everything — dabbling in performance art, journalism, cultural and political activism. And, of course, poetry.

“You got to/live it not just/say it or/play it that’s what this is/all/about,” Sinclair wrote in a 1965 poem.

Upon the dissolution of the White Panther Party in 1971, Sinclair formed and chaired the Rainbow People’s Party, which embraced Marxism-Leninism and promoted the revolutionary struggle for a “communal, classless, anti-imperialist, anti-racist, and anti-sexist … culture of liberation.”

Sinclair proudly and aggressively fought for progressive policies as part of the burgeoning “New Left” movement.

“In those times, we considered ourselves revolutionaries,” he said in 2013. “We wanted equal distribution of wealth. We didn’t want 1 percent of the rich running everything. Of course, we lost.”

Sinclair often kept a toehold in the world of music, managing for a time Mitch Ryder and perhaps most notably MC5, a Detroit-based quintet known for “Kick Out the Jams” and as a hard-rocking forerunner to the punk movement.

In “Guitar World,” Sinclair described “the crazed guerilla warfare we were waging with the MC5.”

Sinclair’s death came only two months after MC5 co-founder Wayne Kramer’s passing.

Sinclair also promoted concerts and festivals and helped to establish the Detroit Artists Workshop and Detroit Jazz Center. He taught blues history at Wayne State University; hosted radio programs in Detroit, New Orleans and Amsterdam; and wrote liner notes for albums by artists including The Isley Brothers and Harold Melvin & The Blue Notes.

Sinclair never stopped promoting — and partaking in — the use of marijuana.

He helped create Hash Bash, a yearly pot celebration at the University of Michigan, and served as state coordinator of the Michigan chapter of NORML, the National Organization for the Reform of Marijuana Laws.

“The only issue I’ve really kept active on is marijuana, because it’s so important,” he told the Free Press. “It’s been a continuous war for 80 years on people like you and me. They’ve got no business messing with us for getting high.”

Sinclair had two daughters from his marriage to Leni Sinclair. They divorced in 1988. In 1989, Sinclair married Patricia Brown.