In 1978, homophobia was ever-present for Sydney's gay and lesbian community.

Homosexuality was illegal in New South Wales, and electroshock therapy was still a widely used "treatment" for same-sex attraction.

Journalist Peter Murphy was a recent university graduate involved in the Gay Solidarity Group, a diverse coalition of activists.

To mark International Gay Solidarity Day the group organised an event: a morning march through Sydney's CBD, followed by a public meeting, and at night, a street party.

This is Peter's account of an evening that started with celebration, ended in severe bloodshed, and changed the course of LGBTI rights in Australia forever.

It was the first Sydney Mardi Gras.

Oxford Street: The party

In the evening of Saturday June 24, Sydney's gay and lesbian community gathered for a street party, starting at Taylor Square.

As it moved down Oxford Street, the geographical heart of the city's LGBTI scene, the crowd built to the hundreds.

"Out of the bars and onto the streets," they chanted.

People in the gay clubs that were littered throughout the inner-city suburb of Darlinghurst heard their cry, and emerged to join the march.

Discarding the approved route, police began prodding the revellers towards Hyde Park.

"Everyone was starting to get a little bit pissed off with how it was going," Peter recalls.

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Revellers invite patrons in gay venues to join them on Oxford Street. ( Supplied: Branco Gaica )

Hyde Park: The resistance

Just 600 metres from where the march had started, and only 15 minutes later, the festival was brought to a halt.

As police tried desperately to disperse the crowd, a tussle broke out.

"Let's go to the Cross," was the cry.

Around 2,000 revellers began marching on to Kings Cross, Sydney's infamous red light district.

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The festival turns into a protest as the crowd refuses to disperse ( Supplied: Branco Gaica )

William Street: A confrontation

As the crowd turned onto William Street, the march music was turned off and the silence was filled with chants.

The festival had become a protest.

"The people were chanting … 'stop police attacks on gays, women and blacks', 'get your laws off our bodies'," Peter says.

As the parade approached Kings Cross, people moved out onto the balconies and awnings to applaud.

Police set up post on nearly every side street, blocking off the roads and sandwiching the crowd.

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Police attempt to direct protesters towards the city, to no avail. ( Supplied: Branco Gaica )

El Alamein fountain: Violence erupts

The crowd arrived at El Alamein fountain and filled the small plaza. The police gave the crowd one minute to disperse.

Linking arms, the protesters began moving out.

"But the police didn't let that happen," Peter says.

"They started arresting people en masse. There was a lot of street fighting."

In total, 53 people were arrested in 45 minutes. Peter was one of them.

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Police begin using force to suppress the crowd. ( Supplied: Branco Gaica )

Darlinghurst police station: Severe bashing

By now it was well past midnight.

The people arrested were taken in paddy wagons to Darlinghurst police station.

Almost 100 other people followed them there from the march. Outside they huddled together for warmth, forming a virtual barricade.

The cold air was filled with the sound of Pete Seeger's protest anthem We Shall Overcome.

Peter was grabbed from the back of a police van and pushed into the station. He was thrown into a room stuffed with gym equipment and severely bashed.

He was left with bruises all around his skull and a severe concussion. He suffered bad bruising to his kidneys and ribs.

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A protester is dragged from a police van into Darlinghurst Police Station ( Supplied: Sydney Mardi Gras )

Known as the 78ers, many of the protesters had their names, addresses and professions published in the media after they were arrested.

Over the months that followed, more protests and arrests took place.

"But in 1984, consenting sexual acts between adult males were decriminalised," Peter says.

"The energy for it really blew out of the first Mardi Gras."

The actions of authorities on June 24, 1978, came to be seen as heavy-handed. In 2016, the 78ers received an official apology from the NSW Government.