MAASSLUIS, Netherlands — The Dutch incarnation of St. Nicholas arrived in the Netherlands on Saturday amid a huge security operation to prevent violent confrontations between supporters and opponents of his helper, “Black Pete.”

The children's character known as Sinterklaas has in recent years been at the center of a heated debate about race in the Netherlands. That's because of his sidekick “Black Pete,” who is often played by white people in blackface makeup.

Opponents contend he is a racist caricature who harks back to slavery, while supporters see him as a harmless figure of fun and an integral part of cherished Dutch tradition.

Thousands of people, including many children wearing “Black Pete” costumes who clambered up trees and street lights to get a better view, crowded into the historic harbor of Maassluis for the nationally televised arrival of Sinterklaas. They were watched over by hundreds of police and security guards amid fears of confrontations.

The celebrations passed peacefully in Maassluis, but police detained 180 anti-Black Pete activists in nearby Rotterdam for defying a ban on protests in that city.

Even Prime Minister Mark Rutte had appealed for calm ahead of the celebrations, using his weekly news conference Friday to tell people on both sides of the debate to “just be normal.”

About 20 far-right activists were easily outnumbered by police as they demonstrated in Maassluis, holding up a banner that said: “We are not ashamed of Black Pete.”

One of them, John Morren, said he was there to defend a Dutch tradition.

“We are demonstrating for the preservation of a children's party,” he said.