PARIS — Demonstrators poured by the thousands into France's streets Tuesday in the latest clash of wills with the government over its plans to raise the retirement age — with protests even taking place on tiny islands. Labor unions aimed to mobilize more than 1 million protesters in what one veteran left-wing leader described as a “citizens' insurrection.”

The nationwide strikes and protests are a crucial test both for President Emmanuel Macron’s government and its opponents. The government says it is determined to push through Macron's election pledge to reform France's pension system. Labor unions and left-wing legislators fighting in parliament against Macron's plans were counting on protesters to turn out massively to strengthen their efforts to kill the bill that would raise the retirement age from 62 to 64.

As large crowds marched in cities and towns, veteran left-wing leader Jean-Luc Mélenchon celebrated “a historic day” of protests and predicted defeat for Macron. In Paris, flag-waving, horn-blowing demonstrators gathered in large numbers for an afternoon march through the capital.

“It's not often that we see such a mass mobilization,” Mélenchon, speaking in the southern city of Marseille. “It's a form of citizens' insurrection.”

In big cities and small villages, rebellion was in the air. On Ouessant, a tiny western isle of some 800 people off the tip of Brittany, about 100 demonstrators gathered outside the office of Mayor Denis Palluel and marched, he said.

Speaking by phone with The Associated Press, Palluel said the prospect of having to work longer alarmed mariners on the island with arduous oceangoing jobs.

“Retiring at a reasonable age is important, because life expectancy isn't very long,” he said.

A first round of strikes and protests brought out between 1 and 2 million demonstrators earlier this month, including many tens of thousands in Paris. Labor leaders were aiming to at least match and even better those numbers Tuesday, with around 250 demonstrations expected around the country.

The government mobilized 11,000 officers to police the protests. Riot police charged and fired tear gas as a small group of men and women in black broke a bank window and splattered the front with pink paint on Paris’ Left Bank. They were part of a small group that infiltrated the huge Paris march. Police said they stopped “radical elements” from damaging store fronts down the road and put a stop to efforts to build barricades.

Police said that three hours after the start of the Paris march, 18 people had been arrested.

The scattered violence came in an otherwise peaceful march, but positions are hardening on both sides as lawmakers begin locking horns in parliament over the retirement reform bill.

On Monday, Macron described the reform as “essential.” His prime minister, Elisabeth Borne, insisted this past weekend that raising the retirement age to 64 is “no longer negotiable.”

Strikers and protesters hoped to prove otherwise.

Rail operator SNCF reported major disruptions, with strikes knocking out most trains in the Paris region, in all other regions and on France’s flagship high-speed network linking cities and major towns. The Paris Metro was also hard hit by station closures and cancellations.

Power workers also demonstrated their support for the strikes by temporarily reducing electricity supplies, without causing blackouts, power producer EDF said.

Jamila Sariac, 60, a civil servant, said the French pension system should be left alone.

“Social protection is a milestone of our society, a milestone that the government wants to break,” she said, adding that strikes would more effectively pressure the government than demonstrations. “We owe it to our elders who contributed to the wealth of France.”

Construction worker Said Belaiba was among travelers whose morning train from Paris to the city of Lyon was canceled, forcing him to wait. Still, the 62-year-old said he opposed the planned reform.

“My job is physically exhausting,” he said. “You can’t keep on over 64.”

Strikes also hit schools, with the Education Ministry reporting that around one quarter of teachers stayed off the job — fewer than in the Jan. 19 first round of protests. French media also reported walkouts in oil refineries. Radio station France Inter played music instead of its usual morning talk shows and apologized to its listeners because employees were striking.