An embarrassing defeat 73 years ago is a preview of the problems China would face in an attack on Taiwan today

• The Chinese Communist troops who stormed Kinmen island in October 1949 expected a quick victory.
• Instead, the Chinese Nationalist forces defending the island routed the attackers.

Around 1:30 a.m. on October 25, 1949, some 9,000 Chinese Communist soldiers stormed ashore on the island of Kinmen, barely 6 miles from China's coast.

They were the first of what was meant to be a 20,000-strong People's Liberation Army force sent to capture the island from Chiang Kai-shek's Chinese Nationalist forces, known as the KMT.

Fresh off a string of victories and with high morale, the PLA expected the battle to be its next triumph, bringing even more territory into the newly established People's Republic of China and moving the PLA one step closer to its final target: the KMT bastion of Taiwan.

PLA commanders believed the defending force to be weak with low morale and expected the fighting to be over within three days. The timing was the only thing the PLA got right.

Three days later, Kinmen was still in KMT hands, three PLA regiments had been effectively annihilated, and the Chinese Communist forces had suffered the first check on their seemingly unstoppable advance.

The plan

The KMT was in near-constant retreat by fall 1949. The PLA, led by Mao Zedong, had crossed the Yangtze River in central China that spring and advanced south over the following months, capturing almost all major cities and ports while suffering few defeats.

Soon all of mainland China was under Communist control. Mao formally established the People's Republic of China on October 1, 1949. Chiang and the rest of the KMT, meanwhile, were retreating to the islands off China's coast. The largest, Taiwan, became the capital of the Republic of China.

With control of the mainland, the PLA set about taking control of the islands, hoping to secure them before launching a final assault on Taiwan.

Kinmen Island, 59 square miles in size and home to some 40,000 people, was essential to this plan.

KMT forces on Kinmen could watch the waters around Xiamen, which the PLA had captured only a few days before, for any mobilization of forces to attack Taiwan.

To take the island, the 28th Corps of the PLA's 10th Army would land roughly 20,000 troops in two groups. Three regiments of some 9,000 men would land on the beaches at night and secure a beachhead so a second force of about 11,000 men could land the following day.

The PLA navy was still in its infancy with few ships or trained sailors, so the troops could only be transported by motor-less wooden fishing boats and junks commandeered from local fishermen. The PLA air force was also nascent, so to avoid the KMT's navy and air force, the first group would have to land at night.

After dropping off the first group under cover of darkness, the vessels would return and pick up the second group.

The battle

The PLA estimated that the KMT had a poorly motivated and trained garrison of about 20,000 troops from its 22nd Army on Kinmen.

In fact, Chiang was determined to defend and hold Kinmen. He sent an additional 20,000 men from the elite 18th Army and a battalion of 21 M5A1 Stuart tanks, operated by troops who had fought in World War II, to Kinmen. (The PLA invasion force had no armored units.)

The island itself was turned into a fortress. Hundreds of bunkers and trenches were built, thousands of mines were laid, and anti-ship obstacles were placed on the beaches.

PLA troops began boarding their vessels around 7:00 p.m. on October 24, but logistics issues and command missteps kept them from setting off until after midnight. Almost immediately, everything went wrong.

The Communist troops arrived and disembarked unnoticed. They approached at high tide, but their late departure left them with little time before the waters receded. The anti-ship obstacles, submerged when they arrived, eventually ensnared all of the PLA boats.

By chance, a routine KMT patrol in the area accidentally set off a landmine, alerting nearby defenders. Searchlights and flares soon exposed the PLA invasion force as it was disembarking, sparking a massive two-hour firefight.

The KMT's 18th Army had coincidentally finished its own landing on the other side of the island around the same time, and the PLA force was soon outnumbered five-to-one.

At dawn, KMT warships and B-25 aircraft joined the fray. They destroyed the stuck boats, trapping the invading force and keeping reinforcements at bay.

Despite the chaos, some PLA units managed to push inland. They seized the town of Guningtou and established a defensive perimeter. But the force, composed solely of infantry, had no hope.

They were soon surrounded by KMT tanks, aircraft, and soldiers. Guningtou was retaken after intense urban fighting on October 27. By day's end, the PLA troops who had retreated to the beaches had also surrendered.

China's growing reach

Of the roughly 9,000 PLA soldiers who landed on Kinmen, about 3,000 were killed and more than 5,000 were captured, effectively wiping out three PLA regiments. KMT casualties included over 1,200 killed and almost 2,000 wounded.

The PLA captured other islands from the KMT, but Chiang's forces held onto Kinmen and several others, including Taiwan. The loss forced Mao and the PLA to acknowledge that invading Taiwan would not be easy.

Later plans for an invasion were delayed by the PLA's involvement in the Korean War and eventually called off altogether. Ultimately, the PLA admitted that it did not yet have the capability to pull off such a grand amphibious feat.

Kinmen itself became a central part of the PRC-Taiwan rivalry. Taiwan fortified it, and China shelled it intermittently — including two rather intense episodes in 1954 and 1958 — until 1979, when the US officially recognized the People's Republic of China.

Beijing has never truly given up on its ultimate goal absorbing Taiwan, which the Chinese Communist Party describes as "reunification," though it has never controlled the island.

At the 20th party congress in October, President Xi Jinping said that although the PRC would like peaceful unification, "we will never promise to give up the use of force and reserve the option to take all necessary measures."

China's military has advanced considerably since 1949, with much of its modernization done with a Taiwan scenario in mind.

The PLA now has the largest navy in the world, with more than 355 warships. It has a roughly 40,000-strong marine corps with modern armored amphibious assault vehicles. Its ground force also has six amphibious combined arms brigades comprising 30,000 personnel with 2,400 vehicles.

China's large and modern missile arsenal, helicopter fleet, and special-forces units are a particular threat to Taiwan.

But the roughly 100-mile strait, where conditions are often poor, and the PLA's lack of real amphibious-assault experience — not to mention Taiwan's own increasingly robust defenses — are major obstacles for the PLA.

But after decades of military upgrades and expansion, Xi may eventually grasp what Mao could only reach.

The Pentagon's 2021 report on the Chinese military said an invasion "of a medium-sized, better-defended island" like Kinmen "is within the PLA's capabilities."