It wasn't much of a war - a 16-day onslaught by Chinese troops in early 1979 - unless you lived here.
"This town was devastated when the Chinese invaded," recalls Duong Thi Nguyen, who now operates a stall in Dong Dang's market and sells everything from noodles to batteries.
She fled just before the invasion and stayed away for 15 years because there was nothing left to come home to.
Down the road, in the provincial capital of Lang Son, Chinese troops fought for a week, house by house, to pry out the town's defenders. Then they turned around and went home. The idea was to punish Vietnam for its invasion of Cambodia, a Chinese ally. Tens of thousands died on both sides, but Vietnamese troops remained in Cambodia for another decade.
Vietnam knows better than most countries how brutal Chinese aggression can be. Officials in Hanoi seem reluctant to discuss their ties with their onetime enemy, but they are enmeshed in the complex project of resolving long-simmering border disputes, encouraging trade, and trying to ensure that China's military doesn't come their way again.
It may seem like something of a historical irony, but diplomats say the Vietnamese look to their ties with the US as a way of strengthening their hand in dealing with the Chinese.
What Hanoi is trying to do
In some ways Vietnam's task is a tightly focused version of what many more developed and more powerful countries are trying to do: forge a solid relationship with one of the world's most dynamic economies and prepare for the day when China begins to exercise more political and even military strength.
Japan, by far the biggest economy in Asia, is expanding its military alliance with the United States even as its businesses make huge investments in China and the government extends loans and other assistance to Beijing. US and Japanese officials insist they are not trying to "contain" China. But defense analysts from both countries say the two governments are enhancing their defense cooperation with at least one eye on China's modernizing military.
Vietnam's approach amounts to a wary embrace, in ways large and small. Ms. Nguyen, for example, sells some Chinese-made flashlights and toothpaste at her stall, but Vietnam restricts the import of many consumer goods to protect local companies from competition. Most of her goods are Vietnamese-made.
Luong Dang Ninh, an official in charge of commerce and tourism for Lang Son Province, proclaims that "the volume of trade has increased very rapidly." But he acknowledges that no Chinese are allowed to operate businesses in the province and says there is "no policy" on letting Chinese live here.
Mr. Ninh is referring to legal trade - Vietnam imports a lot of Chinese construction materials, for example, and exports agricultural and forestry products - but he says there is almost as much smuggling. Even when the border was sealed Vietnamese and Chinese nationals found ways to trade by carrying goods through the mountainous region they share.
The two governments have designated several border areas as places where people can cross for a day to trade, and they are discussing extending the time visitors are allowed to stay in the other country. But during a visit to one such depot in Lang Son Province, the trade seemed to consist mostly of Chinese liquor coming in and Vietnamese prostitutes going over to the Chinese side.
Vietnamese porters pushed bicycles rigged for cargo and laden with Chinese beer through the immigration checkpoint, but then veered off the road to make a long detour around the customs outpost.
On larger issues as well, striking a balance is key.
Vietnam wants to resolve the numerous territorial disputes it has with Beijing, but not at the cost of its claims to the disputed Spratly Islands in the South China Sea that lie atop potentially lucrative resources. Officials in Hanoi want to maintain the large flow of investments from both Hong Kong and Taiwan - a delicate proposition considering that China now controls Hong Kong and vigorously discourages countries from having strong ties with Taiwan, which it labels a "renegade province."
These issues cap a violent history that includes not just the short war in 1979 but more than 1,000 years of Chinese rule of Vietnam.
Nonetheless, Vietnamese leaders have worked hard to improve their ties with China in recent years. The two countries unsealed their borders in 1992, and they have been making progress in solving the lingering border disputes. Vietnam's top leader, Communist Party chief Do Muoi, traveled to Beijing in July to discuss the reversion of Hong Kong to China and indications are that all went well. It was his third visit since 1991.
"Now we're in the love phase," says a Western diplomat who has spent much of this decade in Hanoi, commenting on the state of the Sino-Vietnamese love-hate relationship.
But what do diplomats say is Vietnam's underlying strategy for handling China? "Vietnam's main target is to have close relations with the US," says an Asian diplomat who specializes in Vietnamese affairs. Leaders in Hanoi also see their new membership in the Association of Southeast Asian Nations - a club that now includes every country in the region except Cambodia - as a source of support in facing the Chinese, he adds.
The Western diplomat agrees that Vietnam's top long-term priority and a potential source of leverage in handling China is its relationship with Washington. Both officials spoke on condition of anonymity.
Although Vietnamese officials were happy to discuss border negotiations and trade with China, the country's Foreign Ministry said diplomats were too busy to answer questions about political links or Vietnam's overall approach to its massive neighbor.
The Asian diplomat notes that, as two of the last five communist-run nations in the world, China and Vietnam feel a need to support each other. And it is true that in the heat of the cold war the two countries worked closely together to help evict first the French and then the Americans from Vietnam.
But the Vietnamese, the diplomat adds, "will never lose their suspicion of China. They will not return to the close alliance of the Vietnam War era."