ROME — Italy’s maverick Sardines movement, a silent rebellion against rightist League leader Matteo Salvini, packed a historic square in Rome on Saturday with its first national rally in a backlash against populism.

Tens of thousands of protesters, many waving fish placards, crowded the piazza outside the San Giovanni Basilica in the capital, the latest in a series of demonstrations that squeezes people into historic squares like cans of fish. Organizers estimated more than 100,000 people took part, while police put the number at some 35,000, according to newswire Ansa.

“We’re here because the sea in Italy is full of sardines,” said Lavia Jessica Dell’Anna, from the southern port of Brindisi, who carried a sign around her neck bearing a drawing of the fish and the words “Democracy” and “Anti-Fascist.” She added: “We think Salvini is a big shark, but we are an ocean of sardines and we will eat him alive.”

“I was born in a Europe of peace and democracy and today I feel very threatened by all the movements that are growing in all the states of our beautiful union,” said Luigi Visconti, 16, who brandished a cardboard fish painted blue with the stars of the European Union symbol. “I’m concerned that people are going to offload their bad feelings on the weakest and on the people who are coming here in desperate need of help.”

Sardines also held smaller rallies on the same day in cities including London, Paris and Berlin.

The movement started in Bologna, the capital of the Emilia-Romagna region, which has long been a leftist stronghold and where the anti-migrant Salvini hopes to win elections on Jan. 26. Political banners are banned from the Sardines’ demonstrations, and people hold up placards instead. Although the Sardines are skilled at packing piazzas, their longevity and political impact is in doubt as they have ruled out turning into a political party.

Salvini himself has been defiant. “Bring them on,” he said while campaigning in Bologna. He said the Sardines bring him joy, and he thanked them for their service.

Only subscribers are eligible to post comments. Please subscribe or to participate in the conversation. Here’s why.

Use the form below to reset your password. When you've submitted your account email, we will send an email with a reset code.