BANGKOK — The cream-colored stretch Rolls-Royce limousine crawled past the angry crowds. The queen of Thailand smiled.
But what Queen Suthida Vajiralongkorn Na Ayudhya saw on Wednesday, on a road in Bangkok that has been used for royal processions, may have been sobering.
Antigovernment protesters yelled “my taxes!,” referring to their personal contributions to royal coffers. The police held them back but could not hide the demonstrators’ defiant salutes.
For months now, pro-democracy protesters have gathered by the thousands to call for reforms to the monarchy and military, influential institutions that have dominated Thailand’s power structure for decades.
But the royal limousine’s route on Wednesday was the first time that members of the nuclear royal family had gotten such a close look at the faces of Thais who are openly questioning the monarchy’s exalted position in the country. Thailand’s King Maha Vajiralongkorn Bodindradebayavarangkun and some of his immediate family — including the queen, who is his fourth wife, and his youngest son, the heir apparent — live most of the year in Germany.
The simple act of a royal motorcade driving near an antigovernment protest might not seem a watershed moment. But Thailand is no ordinary constitutional monarchy. It is bound by some of the world’s strictest lèse-majesté laws criminalizing criticism of the crown. During public occasions, Thais are expected to stand for an anthem praising some of the richest royals on the planet. When politicians are given an audience with the king, they typically prostrate themselves and crawl forward in a sideways slither.
But as the protest movement has strengthened over the past three months, taboos surrounding the monarchy have fallen in rapid succession. In Parliament, opposition legislators are demanding an investigation of royal budgets. (After his father’s death in 2016, King Maha Vajiralongkorn took personal control of the crown’s assets.)
In cinemas, people no longer feel obliged to stand for a photo montage of the king that precedes each screening.
And protesters, old and young alike, are demanding that the 10th king of the Chakri Dynasty, who was formally crowned last year with a 16-pound Great Crown of Victory, not be positioned above the country’s Constitution.
“We are going to fight for democracy, fight for freedom, fight for the equality of us as human beings,” a protest leader popularly known as Justin Samutprakan said on Wednesday. “We will not bow, prostrate, crawl ever again.”
“As humans, no one is bigger than anyone,” he added. “No one has power more than others.”
The protesters say they will camp out near Thailand’s halls of power for three days.
Dozens of protest leaders, many students, have been arrested in recent weeks and charged with crimes like sedition that carry imprisonment for up to seven years.
The rally on Wednesday also brought out large numbers of royalist counterprotesters in yellow shirts symbolizing their loyalty to the king. Some had the matching buzz cuts often worn by members of the security forces, suggesting that their defense of the Thai crown was an official duty rather than a personal mission.
As the crowds for both sides swelled on Wednesday, some people in a country conditioned to regular bouts of political violence feared that clashes might break out. But aside from a few scuffles, the antigovernment rally, which pushed past barricades to march toward Government House, was peaceful.
King Maha Vajiralongkorn is now back in Bangkok for weeks, a rarity for a monarch who normally spends no more than a couple days in the country he reigns over.
Last week, Heiko Maas, the German foreign minister, called into question the Thai king’s engagement in politics while living in Germany.
“We have made it clear that politics concerning Thailand should not be conducted from German soil,” said Mr. Maas in a parliamentary session.
Street protests have regularly gripped Thailand over the past two decades. The security crackdowns on some of those mass rallies have been bloody, with dozens of people killed. Over the past few years, outspoken dissidents who fled overseas after criticizing the monarchy and the military have disappeared. Some of their bodies have washed up with obvious signs of foul play.
“Thailand’s international friends should call on the government to stop arresting peaceful protesters, listen to their views, and allow them to freely and safely express their visions for the future,” Brad Adams, Asia director for Human Rights Watch, said in a statement.
The security presence on Wednesday was formidable. About 15,000 police were dispatched to the protest area near Democracy Monument, built to commemorate the end of absolute monarchy in 1932. Public buses were parked to block the path toward Government House, which holds the offices of Prime Minister Prayuth Chan-ocha, the architect of a 2014 military coup who remains the nation’s leader.
Late on Wednesday night, a spokesman for the prime minister’s office said that Mr. Prayuth had instructed the police to take action against those who interrupt royal motorcades or engage in any other acts considered insulting to the monarchy.
Multiple elections in Thailand have been nullified by army coups justified as necessary to protect the monarchy. The putsch six years ago was followed by the passage of an army-drafted Constitution that has eroded democratic institutions further. The Senate, for instance, is now entirely appointed.
The protesters have called for a new charter and for fresh elections, after a national vote last year that was dismissed by some international observers as neither free nor fair.
“We have been imprisoned in a special prison called Thailand for a long time,” said Attapon Buapat, another protest speaker.
The protest movement has woven together disparate strands of dissatisfaction, ranging from frustration with school uniform rules to anger at the lavish lifestyle of the king at a time when a coronavirus ban on international tourism has hit Thailand’s economy hard.
The date of the protest on Wednesday evoked a student-led uprising on Oct. 14, 1973 that led to the toppling of a military dictatorship. During the turmoil, under the reign of the current king’s father, the gates to one of the royal palaces were opened to shelter students fleeing the gunfire.
Three years later, however, security forces and paramilitary mobs killed scores of student protesters. Right-wing rule was restored to Thailand.
On Wednesday evening, after dark fell, a group of protesters tried to extend part of the rally toward a royal palace. But rows of yellow-shirted royalists stood guard. The protesters fell back.