The world learned what TIME once called the most important cold-war textbook lesson of 1958 on a scrubby rock 2 km off the mainland. The island of Quemoy, known in Chinese as Jinmen, sits within easy artillery range of the deepwater Chinese port of Xiamen and astride the shortest direct invasion route to Taiwan. On its beaches in 1949, Kuomintang troops repulsed a Red Army invasion force in a bloody firefight. Chiang Kai-shek had since packed the island with 100,000 troops--nearly a third of his forces. Their presence galled Mao, and he chose the summer of 1958 to instruct the Generalissimo's men in the might of his brash People's Republic. On Aug. 23 the big guns in Fujian province opened fire on several offshore islands controlled by Chiang; Quemoy alone was hit with 50,000 rounds of artillery fire. The next day an additional 40,000 rounds pounded the island, which absorbed an average of 10,000 shells a day for the next five days. On Aug. 29, the Fujian commander broadcast a message to Quemoy's beleaguered Nationalist garrison: No military works can avoid complete destruction under the assault of our modern army and air force... The landing on Quemoy is imminent... Surrender! Given the Red Army's 5-to-1 firepower advantage in the Strait, the command was not so impertinent. Mao showed greater hubris in challenging the paper tiger that prowled behind Chiang's forces. During a meeting of the Politburo Standing Committee at the seaside resort of Beidaihe, which he chaired in his bathrobe, the Great Helmsman explained that he meant to test America's determination to defend Taiwan. Washington's response seemed clear: the Pentagon sent two aircraft carriers steaming toward the area to join the four already patrolling as part of the Seventh Fleet. On Sept. 7 they began escorting Nationalist ships trying to resupply Quemoy. Aboard each of the carriers of the fearsome Task Force 77 stood a single A3D bomber. Should the signal come from Washington, cabled a TIME correspondent aboard the U.S.S. Midway, the deck beneath the A3D would open, and up would come an elevator to tuck into the plane's belly a nuclear bomb capable of reducing all Peking and its masters to radioactive dust. Yet the U.S. could not commit explicitly to defending Chiang's islands precisely because the threat of nuclear war had become so real. A top secret State Department memo written 10 days before the shelling of Quemoy notes that Pentagon plans called for defending the island with nuclear strikes deep into Communist China, including military targets in the Shanghai-Hangchow-Nanking and Canton complexes where population density is extremely high. This would, of course, entail millions of non-combatant casualties. Moscow, although peeved at not having been informed in advance of Mao's plans, declared that the use of atomic weapons against China would be grounds for a Soviet nuclear attack on the U.S. Under our present strategic concept, the State Department memo noted, this would be the signal for general nuclear war between the U.S. and the U.S.S.R. Four years before the Cuban Missile Crisis, the world thus learned the terrifying terms of brinkmanship. America's allies maintained a discreet silence over the conflict, and even Washington showed mild displeasure over Chiang's buildup of so many troops on Quemoy. But neither did U.S. planners feel they could back down in the face of Chinese communist aggression. For his part, Mao seemed to rethink the purpose of the shelling with each passing week. At first he told colleagues America needed to be taught a lesson for its gunboat diplomacy in the Middle East. Although the Soviets had the impression Beijing was preparing to invade Taiwan, Mao said only that the Red Army might take Quemoy, and only if the opportunity arose. Most likely the Helmsman hoped to convince Taiwanese that Chiang could not protect them, and to rally mainland China's masses behind his nascent Great Leap Forward. The stalemate was broken by a force that may have surprised Mao even more than the Americans: Chiang's troops. Much-maligned for collapsing in the face of the communist advance in 1949, the Nationalists had in the intervening decade been transformed into an army so dedicated that at one site on Quemoy, where the Republic of China flag was knocked down 17 times by mainland fire, troops restored the colors each time. In the air, outnumbered KMT pilots downed 29 Communist MiGs, to the loss of only one plane. At sea, although they never quite succeeded in breaking the Chinese blockade, the Nationalists began to restore the flow of supplies to Quemoy by switching to smaller, more maneuverable landing craft. The futility of continued shelling became obvious. After a month of talks with the U.S., Mao declared a unilateral cease-fire on Oct. 6. Though the guns were ordered to fall silent for just a week, the decision effectively ended the siege of Quemoy. Three weeks later Beijing would offer to bombard the island only on alternate days; within two years Taipei had taken up the offer, and the two sides traded symbolic and surreal fire until 1978. When he claimed that he actually favored leaving KMT troops on Quemoy--as a tripwire with which to tweak the U.S. whenever he chose--Mao seemed only self-serving. Beijing has not yet mothballed that strategy. These days, however, troop levels on Quemoy are one-fifth of their previous number, and in recent years Taipei has opened the island to tourists. Despite loud saber-rattling this past summer from Beijing, the U.S. sent no carrier battle groups to the Taiwan Strait, and the Quemoy garrison did not even raise its alert level. Quemoy, though still bristling with weaponry, has assumed the musty air of other cold war frontiers. The massive green loudspeakers that once broadcast propaganda across the kilometer of water separating the warring sides now blast Taiwanese pop music at night. On the shore below, a sentry continues to watch for the frogmen that once crawled ashore here; fortunately for him the island on which the saboteurs once trained--a desolate pebble easily visible through binoculars just offshore--is now dominated by a tall, red-roofed and eerily empty hotel. Further west the commander of an air defense battalion shows off his 20-mm machine gun with a boyish enthusiasm that belies the island's martial past. I like Jinmen because I like free, he says in English. Meaning the cause of freedom, thought to be at stake in 1958? He shakes his head--a gesture that suggests how much the standoff with Beijing has become pure theatrics. His wife, he explains slyly, lives in Taiwan.