When the Plastic People of the Universe, the rock band founded by bassist Milan Hlavsa — who died Friday in Prague, Czechoslovakia, of lung cancer at age 49 — raged against Czechoslovakia's Communist government during the late 1970s, the machine actually ground to a halt.

The 1976 arrest of two Plastic People members for disturbing the peace inspired future Czech President Vaclav Havel to write Charter 77. His human-rights declaration, with its defense of "life's intrinsic desire to express itself freely, in its own authentic and sovereign way," laid the groundwork for the 1989 revolution that liberated the country from its hard-line Communist rulers.

Hlavsa, born in 1951, worked as a butcher while performing in such bands as the Blue Monsters, the Vagabonds, the Undertakers and the Primitives. In 1967 he heard The Velvet Underground & Nico for the first time.

"I was totally, absolutely in a trance," he told writer Richie Unterberger. "It was raw, clear, transparent. Thanks to this encounter I did not throw my guitar in the dustbin."

Under the influence of the Velvets and other American bands, including the Doors, Fugs, Captain Beefheart and Frank Zappa's Mothers of Invention (whose song "Plastic People" inspired their name), Hlavsa formed his own Plastic People less than a month after Czechoslovakia was invaded by Soviet tanks and Polish troops in September 1968.

Along with keyboardist Josef Janicek and artistic director Ivan Jirous, the Plastic People performed as professional musicians subsidized by the government until January 1970, when their license was revoked due to their refusal to follow Ministry of Culture rules. The band went underground, performing at "weddings," outlaw parties and tribal "happenings," scrounging its equipment together out of spare electronic parts. In 1973 Hlavsa formed DG 307, a side project with poet/sculptor Pavel Zajicek.

The Plastic People recorded their first album, Egon Bondy's Happy Hearts Club Banned, in 1974. A loose-limbed slab of grungy psychedelia containing surprisingly little political content, the album was smuggled out of the country and released in 1978.

A Hundred Points, a tape of the Third Music Festival of the Second Culture that took place at Havel's country home, was released in 1977. The band's second album, Passion Play, was recorded at Havel's farm in 1978, while the police staked out the area. The group also recorded Leading Horses (1983), the unreleased Slaughterhouse (1984) and Midnight Mouse (1987).

The Plastic People broke up in 1988, following a dispute over what compromises the group was prepared to make to perform at a 1987 Czech rock festival.

Hlavsa subsequently formed Pulnoc (Czech for midnight), who toured the United States in 1989, several months prior to the Velvet Revolution in November, which put Havel into power. Pulnoc recorded City of Hysteria in New York in 1991.

"Hlavsa was a terrific student of Zappa, Beefheart and the Velvet Underground," said former Captain Beefheart guitarist Gary Lucas, who performed with Pulnoc when they appeared in New York in 1998. "I definitely felt a Beefheart connection, especially rhythmically."

In 1997 the Plastic People reunited to celebrate the 20th anniversary of Charter 77. That same year Hlavsa formed another band, Fiction. In 1999 the Plastic People performed at the White House with Lou Reed.

Hlavsa was recording new music with the Plastic People when he learned that the lung cancer he fell ill with in May had spread to his brain.