In the early hours of October 25, 1949, some 9000 Chinese Communist soldiers landed on the island of Kinmen.
The first 20,000-strong People's Liberation Army force was sent to capture the island from the Chinese Nationalists.
After a string of victories, 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 fighting was expected to be over within three days. The timing was the only mistake the PLA made.
Kinmen was still in the hands of the KMT three days later and the Chinese Communist forces had suffered their first check on their seemingly unstoppable advance.
In 1949, the KMT was in retreat. Almost all major cities and ports in central China were captured by the PLA over the course of a few months after they crossed the river.
All of mainland China was ruled by the Communists. The People's Republic of China was established by Mao. The rest of the KMT were moving to the islands off the coast of China. Taiwan became the capital of the republic of china.
The PLA wanted to take control of the islands before attacking Taiwan.
Kinmen Island is 59 square miles and is home to 40,000 people.
The waters around Xiamen, which the PLA had captured a few days before, could be watched by the KMT.
The 28th Corps of thePLA's 10th Army would land 20,000 troops in two groups. A second force of 11,000 men would be able to land the next day because three armies of 9000 men landed on the beach at night.
ThePLA 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. To avoid the KMT's navy and air force the first group had to land at night.
The vessels would come back and pick up the second group after dropping off the first group.
About 20,000 troops from the 22nd Army on Kinmen were estimated to be in the garrison by the PLA.
The man was determined to hold the man. More than 20,000 men from the 18th Army and a battalion of 21 M5A1 Stuart tanks were sent to Kinmen. There were no armored units in the invading force.
The island became a fortress. Thousands of mines and anti-ship obstacles were placed on the beaches.
Logistic issues and command errors kept PLA troops from leaving until after midnight. Everything went wrong right away.
The communist troops were not noticed. Their late departure left them with little time before the water subsided. The anti-ship obstacles got in the way of the boats.
A landmine was accidentally set off by a patrol in the area. The firefight began when the PLA invasion force was exposed as it disembarked.
The KMT's 18th Army finished its landing on the other side of the island around the same time as the PLA force.
The B-25 aircraft joined the fight at dawn. The invaders were trapped and kept at bay by the destroyed boats.
Some units of the PLA pushed inland. The town of Guningtou was taken over by them. The force had no hope.
They were surrounded by military equipment. The troops who retreated to the beaches surrendered by the end of the day.
More than 5,000PLA soldiers were captured and over 3000 were killed when they landed on Kinmen. Over 1,200 people were killed and over 2,000 were wounded.
The KMT held onto Kinmen and several others, but the PLA captured other islands. Mao and the PLA realized that invading Taiwan would be difficult.
Plans for an invasion were put on hold due to the involvement of the PLA in the Korean War. The PLA admitted that it didn't have the ability to pull off such a feat.
Kinmen was a central part of the rivalry between the PRC and Taiwan. When the US officially recognized the People's Republic of China in 1979 it ended China's bombardment of it.
Beijing has never given up on absorbing Taiwan, even though it has never been in control of the island.
"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," the president said at the congress.
The modernization of the Chinese military has been done with a Taiwan scenario in mind.
The PLA has the largest navy in the world. There is a large marine corps with amphibious assault vehicles. There are six amphibious combined arms brigades with 30,000 personnel and 2,400 vehicles.
China's missile arsenal, helicopter fleet, and special-forces units are threats to Taiwan.
The roughly 100 mile strait, where conditions are often poor, is a major obstacle for the PLA.
After decades of military upgrades and expansion, Xi may be able to comprehend what Mao could only achieve.
Kinmen is a medium-sized, better-defended island that the Chinese military is capable of invading, according to a Pentagon report.