HONG KONG — Undaunted by Chinese troops drilling just across the border and Beijing’s threats about perishing by fire, Hong Kong’s protesters on Sunday amplified their calls for freedom and democracy. They held a huge rally in which hundreds of thousands spilled peacefully over the cramped boundaries set by police. Some protesters brought their children. Everyone sweltered under the subtropical summer sun, then got soaked in a torrential cloudburst. Most of the protesters then carried on for hours more in the lingering rain, umbrellas deployed and feet wet, calling for “Free Hong Kong” and “Democracy now!”

If there’s one message that came across loud and clear, it is that Hong Kongers, in defying Beijing, may be taking on the Goliath of modern tyrannies, but even against terrible odds, they are committed to this contest. That’s how much they value freedom.

At this most recent Sunday protest, the police had tried to bottle up the protesters inside the gates of Hong Kong’s Victoria Park, by approving plans for an assembly to be held strictly within the park, but denying permission for the protesters to follow their usual custom of marching across town to the central business district. As it turned out, most of the protesters marched anyway. They converged on the park in such massive numbers that the whole thing turned into a protest march — beginning quite simply by way of their coming and going through the surrounding streets. Protesters overflowed onto the roads, jammed onto the flyovers and footbridges and ultimately filled the carriageways along the harbor front. In a marathon protest that extended from mid-afternoon into the evening, many then marched the entire two miles of the originally proposed route, chanting slogans in Cantonese such as “add oil!” (local slang, meaning “keep going!”).

Hong Kong’s government put out a press release lamenting this unauthorized march, conceding that it was “generally peaceful,” but complaining that the protesters’ use of the thoroughfares seriously affected traffic and caused “much inconvenience to the community.”

Speaking as a reporter who was there on Sunday covering the entire event, I’d say that much of the community was actually busy taking part in the protest — which was inconvenienced during the first few hours by the traffic. Organizers estimated the turnout at 1.7 million, or close to one-fifth of Hong Kong’s population. The police put it at 128,000, which sounds absurdly lowball. I’d wager no one knows for sure, but this I can tell you: it was massive. People just kept coming. For hour after hour. They filled the huge main rectangle in the park, they crammed into every street in the area that I tried to navigate. They formed up with their umbrellas into a colorful river of protest that flowed for hours along the route that their own government — so concerned about “traffic,” so grimly unresponsive to the genuine rights and demands of the actual community — did not want them to take.

Nor was this protest in any way like the young, relatively small and sometimes violent “flash mobs” that have been grabbing headlines in recent weeks. This Sunday’s protest put on display the tremendous breadth and depth of Hong Kong’s democracy movement. There were gray-haired protesters, middle-aged couples, teenagers in face masks, you name it — including a passing bus driver, who gave a thumbs-up, and got a massive cheer in response, as he inched his bus through the crowd.

Perhaps most intriguing were the parents who despite the warnings surrounding this protest brought young children. I counted dozens in the park, merely within my immediate lines of sight, and spoke with some of them. One after another, these parents told me the protests are all about their children. These are people who know what freedom means, and see it as a vital legacy for the next generation. One couple who’d brought their six-year-old daughter and three-year-old son said they’d come as a family to show the government that the protesters are peaceful, and to begin teaching their children what freedom is about. Pointing at the six-year-old, the mother said, “She’s old enough to understand.” Another couple — the father carrying the four-year-old son on his shoulders, the mother pushing the one-year-old daughter in a stroller — told me “it’s all for our kids.”