PARIS — It was supposed to be the site of the biggest airport in western France, a hub for cargo traffic and Concorde flights.
But instead, it became the center of a utopian experiment and an entrenched protest camp, one that challenged the government of President Emmanuel Macron.
In 1970, 3,700 acres of fields and woodland near the village of Notre-Dame-des-Landes were chosen for the new airport to satisfy a need first identified in 1965.
But in 2009, hundreds of protesters started squatting on the land, complaining of the project’s noise and the threat to wildlife. They set up shelters made of corrugated iron, wood and earthworks.
In January, they won an important victory when the airport was shelved by the government because of the divisions surrounding the project.
The only problem: The squatters’ camp had to go, too, the government said, and they didn’t want to leave.
On Monday, before dawn, the police began to clear the camp, with about 2,500 riot officers storming the area with armored vehicles and tear gas, destroying barricades and razing some of the activists’ holdouts along the way.
About 250 protesters fought back with petrol bombs, rocks and other projectiles. According to local officials, 28 police officers and one protester were wounded, although activists in the encampment said other protesters had been hurt and treated on-site.
Seven people have been taken into custody so far.
The police continued their clearing operation on Tuesday. And on Wednesday, another showdown loomed as security forces began their third day of intervention, while activists called for a peaceful gathering on the site.
“If you want to do something that goes beyond you today, find the courage to come here to defend a zone that is a laboratory for the future and the common good, against the forces of the ancient world,” the protesters’ main account said on Twitter on Tuesday.
The move to clear the site is the latest episode in an airport project that stretches back more than 50 years. An oil crisis in the 1970s and the expansion of the country’s high-speed rail network stalled the plan for decades before it was reactivated in 2000.
The protesters call the area Z.A.D., the French initials for Zone to Defend — a play on the official name, Zone for Future Development
Initially, the airport protest centered on complaints about noise and claims that the land was an important habitat for wildlife. Some also argued that the project was a waste of money — given that the nearby city of Nantes already had a functioning, if small, airport.
As the project gained a second life, a group including environmental activists, local farmers and anticapitalists swung into action. They created an alternative society on the site, opening a library, a bakery, a weekly market and dozens of other buildings and services.
Volunteer doctors treated activists who fell ill, and collective kitchens were created. Some activists grew medicinal plants, while others bred cattle or raised sheep.
The activists set up common rules that they called limits, gathered in local assemblies, and every two weeks summoned 12 people to resolve conflicts.
As the authorities began clearing the site this week, the clashes made headlines across France, where Mr. Macron’s attempts to overhaul the economy have already been met by a wave of strikes and protest movements.
Thousands of supporters of the squatters gathered in Nantes, Paris and other parts of France to protest the violence at the site. Left-wing politicians and environmental activists criticized the police deployment and the use of armored vehicles to destroy the installations. Lawmakers from Mr. Macron’s own parliamentary majority called for a pause in the eviction operation.
“Let’s stop!” François-Michel Lambert, a lawmaker and member of Mr. Macron’s party La République en Marche (the Republic on the Move) said on France Info.
“Only politics, only peace is the good solution, not the clash that ends in the destruction of one, which will never be the victory of the other,” he said, referring to the face-off between the riot police and the squatters.
Gérard Collomb, the French interior minister, said on the TV news channel LCI that the clearing of the area could last until the end of the week.
The government has said that the protesters were offered alternative housing, but that nobody could stay unless they filed individual, agricultural projects to the authorities.
A local official, Nicole Klein, said on Tuesday that she had not received any project submissions, though some activists said they had started legal procedures to claim some of the land.