Narration: Korea, summer 1950.

The United States leads the United Nations into a war against communism in Asia.

In winter, under attack from the Chinese communists, the U.N. troops are thrown into full-scale retreat.

Interview: Lt. Col. Charles Bussey, U.S. Army

"It was a rout exactly like the one that Napoleon faced leaving Russia. We ran head-long, helter-skelter, pell-mell, trying to get to Pusan, trying to get back to Japan. It was disgusting."

Narration: The Cold War has become a hot war.

August 1945. At the end of the Second World War, the Japanese army that had occupied Korea for 35 years surrenders.

Interview: Kim Ren Ok, North Korean

"During the Japanese occupation, they forced us to follow the Japanese lifestyle, speak the Japanese language, use Japanese law. When we were liberated, we welcomed the soldiers."

Narration: Russian and American troops liberated Korea -- meeting together just as they had in Germany.

As occupying powers, the Soviet Union and the United States agreed to divide Korea along the 38th parallel -- as a temporary measure. South of the divide, the Americans were in control.

Interview: Niles Bond, U.S. State Department

"We made the Republic of Korea really, er -- between the Pentagon and the State Department."

Narration: American generals installed a hard-line anti-communist -- Syngman Rhee.

Interview: Niles Bond, U.S. State Department

"His charm is somewhat deceptive because he's also very tough, he's absolutely unforgiving, er, very patriotic. And he's not nearly as sweet as he looks."

Narration: Rhee was appointed as first president of the new Republic of Korea in 1948.

American troops withdrew.

North of the 38th parallel, the Russians were in control.

They established a communist regime through a network of people's committees. Kim Il Sung, who had spent the war in the Soviet Union, was groomed for power.

Interview: Ten San Din, Soviet adviser to North Korea

"He was a very handsome young man, always smiling. Everybody liked him in Korea. He made a very good impression. He was the national hero of the Korean people."

Narration: The Democratic People's Republic of Korea was proclaimed with Kim Il Sung as its president.

As Soviet troops withdrew, Kim dreamed of uniting Korea under communism.

Interview: Col. Petr Simchenkov, Soviet High Command

"Kim Il Sung understood that to resolve the problem of unifying the two Koreas was very difficult -- that he would need help. Of course the help he was hoping to get would come from the Soviet Union."

Narration: In March 1949, Kim Il Sung went to Moscow: his secret agenda to seek Stalin's permission to invade the South.

Archival Footage: Kim Il Sung

"The reason I'm visiting the Soviet Union is because I want to strengthen the relationship between Russia and North Korea."

Narration: Stalin, preoccupied with crisis in Berlin, rejected Kim's request to invade.

By the end of 1949, the international situation had been transformed. The Soviets detonated their first atom bomb.

And the communist revolution in China was finally successful. Mao Tse-tung proclaimed the People's Republic of China.

A treaty of friendship between Mao and Stalin created a communist global alliance, opening a second front to the Cold War in Asia.

Stalin was now confident that the United States lacked the will to respond to events in Asia. In April 1950 he finally gave approval for Kim Il Sung to invade South Korea.

June 25, 1950: the North Korean Army launches its surprise assault on the South.

Interview: Hong An, student, Seoul

"I remember vividly, even today, the day the war broke out. It was Sunday morning. And we heard this kind of remote ... the roaring noise from the North."

Narration: Equipped with Russian tanks and artillery, and directed by Soviet advisers, 10 combat divisions of the North Korean army flooded south.

Interview: Yan Von Sik, North Korean army

"We believed that we had to fight for our motherland, for our people, for our leader Kim Il Sung. We believed it would be better to liberate the South and to unify Korea. That's what we were fighting for."

Narration: Sunday morning in Korea -- Saturday evening in Washington. The Sunday papers prepare to go to press.

Interview: Han Pyo Wook, South Korean Embassy, Washington

"It was Saturday evening. I got a telephone call from the UP duty officer saying that Korea had been invaded by North Koreans. And momentarily the remark stunned me so much that I didn't know what to say, whether he was joking with me or whether he was really sure."

Narration: Senior officials were recalled that night to the State Department.

Interview: Lucius Battle, assistant to the U.S. secretary of state

"And about midnight there was a call from President Syngman Rhee. I took the receiver and he said, 'Please ask American government to rush necessary help.'"

Narration: The South Korean ambassador went immediately to the State Department to see Assistant Secretary Dean Rusk.

Interview: Han Pyo Wook, South Korean Embassy, Washington

"Noting with grave concern the armed invasion of the Republic of Korea by armed forces ..."

Narration: The following day, the Security Council met. Moscow was boycotting the United Nations because of its refusal to admit communist China.

Archival Footage: President of the United Nations Security Council:

"Those in favor will please raise their hands ..."

Narration: The United States seized the opportunity to condemn North Korean aggression.

Archival Footage: President of the United Nations Security Council

"... carried by 9 votes for; 1 against and 1 abstention."

Narration: Two days later, the Security Council voted to create a United Nations military force to defend South Korea.

Archival Footage: Warren Austin, U.S. delegate to Security Council

"This is in fact an attack on the United Nations itself ..."

Narration: Under the U.N. flag, soldiers from 16 nations would fight against communism.

Interview: Han Pyo Wook, South Korean Embassy, Washington

"We were elated. We felt very, very good, very encouraged. We felt furthermore ... we felt that probably Korean unification was to come about as a result of the resolution itself."

Narration: President Truman addressed the nation.

Archival Footage: President Truman

"The feeling at that time was that a military operation of this magnitude could not possibly have been taken without the support of the Russian military. In other words it was concluded right at the beginning that this was a movement ... this was something happening in the context of the Cold War."

Narration: The United States mobilized for war. The reserves were called up.

Interview: Lucius Battle, assistant to the U.S. secretary of state

"Everybody was agitated, getting ready to go overseas. There were all sorts of feelings, trepidation, expectancy. There was quite a feeling of wanting to stop the communists from taking over anywhere in the world. They wanted to stem the tide of communism."

Narration: Gen. Douglas MacArthur, the allied supreme commander in Tokyo and the legendary victor of the Pacific war, was appointed to lead the United Nations' forces.

Interview: Brig. Gen. Edwin Simmons, U.S. Marines

"He was worshipped in Japan. This man had a tremendous ego and it had been fed for all these years. I do believe he was at this point ... he felt that he was infallible."

Narration: The nearest troops to Korea were the American occupation force in Japan -- few of whom were ready for combat.

Interview: Lt. Col. Charles Bussey, U.S. Army

"The lifestyle involved a lot of leisure. Our life was lived through the Sears Roebuck catalogue. We bought nylons and whatnot for the native girls and that sort of thing. It was a ... it was a good life."

Narration: The U.S. Task Force sent to Korea didn't imagine their stay would be for long.

Interview: Lt. Col. Charles Bussey, U.S. Army

"As a matter of fact, we were told to take our athletic equipment and leave everything else behind because we'd only be gone for maybe six weeks. We'd have a show of force in the field and those gooks would go back across the 38th parallel and we'd come home."

Narration: It wouldn't be that easy. Rhee's South Korean army was in retreat.

Two divisions threw their weapons away and joined the refugees fleeing the communist advance.

Interview: Gen. Paik Sun Yup, South Korean Army

"As soldiers, we did our utmost. But the overall situation was going against us. The North Korean army achieved its initial objective. It captured Seoul in three days."

Narration: With the capture of the southern capital, Kim Il Sung won a great victory for communism.

Interview: Kim Ren Ok, North Korean nurse

"When we got to Seoul the army told us the campaign was finished. They told us political reforms will follow. Now the country will be unified with ease. We didn't think there would be any more war."

Narration: American troops fared no better than the South Koreans. With no effective anti-tank weapons, the American line collapsed.

Within days, American troops were reeling back in disarray, under assault from the tiny communist regime of North Korea.

Interview: Lt. Col. Charles Bussey, U.S. Army

"We had equipment left over from World War II. We were in very poor shape for everything. We were not ready to fight a war -- that's what it amounts to. That's the long and short of it."

Narration: Around the world, America's allies rallied behind the United Nations flag. The British prime minister pledged his support.

Archival Footage: Clement Attlee, British prime minister

"If the United Nations organization was not to go the way of the old League of Nations, it was absolutely and imperatively necessary that a halt should be called."

Narration: Troops from 15 nations began to arrive in Korea to join the Americans in the U.N. army.

Gen. MacArthur took a gamble to turn the tide of the war.

With the U.N. forces driven back to a tiny enclave at Pusan, a vast seaborne invasion, 150 miles behind enemy lines, would attempt to sever and then roll back the North Korean advance.

Dawn, September 15, 1950.

The largest invasion fleet since the Second World War bombards the port of Inchon.

American and Korean marines go ashore in huge numbers.

Interview: Chea Yong Ghu, South Korean marine

"There was a sea wall there -- cut stone. It had to be scaled. Actual landing conditions were terrible. Part of the city was on fire. It was a rainy day and the rain was mixing with the smoke and the fire and the smoke of the bombardment. If those beaches had been defended by Japanese or German troops of the same quality as the Germans and Japanese were in World War II, we would have been lucky to get ashore and we might not have been quite so lucky once we got ashore."

Narration: Within two weeks, U.N. troops were engaged in a fierce battle to recapture the southern capital, Seoul.

50,000 civilians were killed in the crossfire.

Interview: Hong An, student, Seoul

"My house was located in a hillside and there was a crossfire between the U.N. forces and the North Korean People's Army on the northern side. Finally my father told us that it would be better if our family split up, at least somebody will survive this war."

Narration: After finally recapturing Seoul, MacArthur reinstated Syngman Rhee in the parliament building. MacArthur's association with Rhee's increasingly vicious regime caused concern in Washington.

Interview: Lucius Battle, assistant to the U.S. secretary of state

"Syngman Rhee was a difficult man to back. And once he was in power, it was very difficult for us to do anything. It was not up to us to change the government. And there was no other alternative obviously available anyway."

Narration: Rhee's jubilant army was the first to cross the 38th parallel into North Korea.

Interview: Lee Jae Jeon, South Korean army

"When we counterattacked across the 38th parallel, every one of us, soldiers and people, thought now the drive was on to unify the whole Korean peninsula."

Narration: The U.N. troops too advanced into North Korea. MacArthur's war aim now appeared to be hot pursuit of the invader.

Interview: Lt. Col. Charles Bussey, U.S. Army

"I thought we'd won the war. I shouldn't laugh at this point, but I have to. I really thought that we'd won the war and I think that was the general feeling. And we went north with high hopes."

Narration: The giant Yalu River marks the boundary between North Korea and China. Across this border, the Chinese leadership followed the war with alarm. They feared the American army in North Korea would invade the Chinese mainland.

Interview (1993): Shi Zhe, Foreign Ministry, Beijing

"If North Korea was defeated, only the Yalu River would separate us from the Americans. We couldn't accept this nor the risk of American aircraft disrupting the reconstruction of our country."

Narration: From devastated North Korea, an urgent message went out to Beijing.

Interview: Kan San Kho, deputy minister of interior, North Korea

"A government delegation was sent to Mao Tse-tung. 'What can we do?' they asked. 'We can't retreat. They're attacking us from the air, from the sea, and by land. There is very little of the North Korean army left. Many have died. What can we do now?'"

Narration: The communist leadership in Beijing was deeply divided over intervention. Mao received secret cables from Stalin telling him to enter the war to save North Korea. Wanting to assert China's power in Asia, Mao was agreeable. Meanwhile, the U.N. and South Korean armies continued the race north.

On October 19, Pyongyang fell. It was the only communist capital ever to fall to the West during the Cold War.

Interview: Brig. Gen. Edwin Simmons, U.S. Marines

"MacArthur had the bit in his teeth. He was pursuing a defeated army. The race to the Yalu was on."

Narration: MacArthur was surprised to be summoned to Wake Island in mid-Pacific for a meeting with President Truman. MacArthur assured his commander in chief there was no possibility of China entering the war.

He took the award of yet another medal as a signal that he could continue the advance toward China. When the president asked him to stay for lunch, MacArthur refused.

While Truman and MacArthur were talking, Mao ordered the Chinese army, called the People's Volunteers, to enter Korea. Half a million Chinese began to cross the Yalu River and waited -- for the U.N. forces to approach the border.

As they crossed the Yalu in enormous numbers, the Volunteers sang this song.

Interview: Chan Boliang, Chinese People's Volunteers

That's how it goes!"

Narration: Unaware of the massing of the Chinese troops, the U.S. Army paused for Thanksgiving. Roast turkey and cranberry sauce were served up. MacArthur and his soldiers still thought the war would be 'over by Christmas.'

Interview: Lt. Col. Charles Bussey, U.S. Army

Narration: Next morning, 300,000 Chinese attacked.

"The first aim of the Volunteers going into Korea was to defend our homes and country, the Motherland. We couldn't allow others to cross the Yalu River and invade us. But also we wanted to help the Korean people."

Narration: As in China's long civil war, Mao believed that greater motivation could defeat an enemy with superior arms.

Interview: Chan Boliang, Chinese People's Volunteers

"The reaction when China came in was that we had a whole new war, a whole new situation. It was a very terrifying situation and one that was extremely troubling."

Narration: In the next swing of this seesaw war, U.N. forces across North Korea were thrown back, abandoning vehicles and equipment.

Interview: Lt. Col. Charles Bussey, U.S. Army

"I'm not aware of any other movement of Americans that were as futile as that rout was, and it was a rout."

Narration: American soldiers called it 'bug out' fever.

Archival Footage: President Truman

"We are fighting in Korea for our own national security and survival. We have committed ourselves to the cause of a just and peaceful world order through the United Nations. We stand by that commitment."

Narration: At a Washington press conference, journalists repeatedly pressed Truman on the possible use of the atom bomb.

Interview: Robert J. Donovan, White House press correspondent

"It went on and on and on just like that -- the president not being able to shut this thing off. And until people began to think that maybe we were going to use the atomic bomb. The bulletins about the president's press conference went around the world immediately. And that caused incredible alarm."

Narration: British Prime Minister Clement Attlee was sufficiently alarmed to fly to Washington for crisis talks.

Archival Footage: Clement Attlee, British prime minister

"My aim in these talks is to align our policies in the new and troubled situation in the world and to find the means of upholding what we both know to be right."

Narration: Next day, Truman assured Attlee that there were no plans to use atomic weapons.

Interview: Nikolai Fedorenko, Soviet Foreign Ministry

"I think the Americans understood it would be tit-for-tat. If they use it, we will use it. We had an agreement with the Chinese. That's why they didn't use the atomic bomb."

Narration: At home that winter, for many American families, the pain began with a call at the door.

Interview: Florence Galing, Army officer's wife

"The 29th December, the doorbell rang. It was on a Friday. I had just washed my hair and I opened the door and there was a boy delivering a telegram. And he turned on his heels and left and I knew the telegram was going to tell me either he was dead or alive. And when I opened it I just thanked God that he was 'missing in action'. As far as knowing when he became a prisoner, that wasn't for another year. Even though we knew he was in a camp, I never knew from day to day how he was doing. I never knew from letter to letter if he was alive. You know, so I always held out hope that he would come home, but I never could say that he would come home."

Narration: Retreating U.N. soldiers adopted a scorched earth policy.

After withdrawing from Hungnam, American engineers blew up the dockside.

The Chinese, rapidly advancing, recaptured the northern capital, Pyongyang.

At the beginning of 1951, Seoul fell again to the communists.

Gen. Matthew B. Ridgway was appointed by MacArthur as the new field commander. At last, U.N. troops began to slow the Chinese advance.

Interview: Brig. Gen. Edwin Simmons, U.S. Marines

"The defeatism and the bug-out fever and so forth that had afflicted the 8th Army before was eradicated."

Narration: From the beginning, the United States enjoyed air supremacy.

Interview: Sen. John Glenn, U.S. pilot

"When I was flying up along the Yalu in the F-86, the Saber, we were using tactics that had literally been used in World War I and World War II, except we were flying jets at much higher speed."

Narration: When Russian MIG-15 fighters with well-trained Russian pilots were sent to the war zone, they posed a challenge to American supremacy.

Archival Narration:

"Our mission was to go there to train pilots. But later we ended up as participants in the Korean War."

Narration: The presence of Russian pilots risked bringing the Soviet Union into direct conflict with the United States.

Interview: Yevgeni Pepeliayev, Soviet pilot

"Our government and the military demanded complete secrecy. We must never let the enemy know they were fighting Russians."

Narration: When the U.S. deployed the F-86 Saber, they slowly won back mastery of the skies. This enabled American aircraft to keep up a constant offensive on ground targets.

Interview: Sen. John Glenn, U.S. pilot

"For ground attack we were flying the F-9F, the Panthers. And they would carry a large bomb load and we could carry a couple of 1,000-pound bombs on that airplane, and on some flights 100-gallon napalm tanks with the white phosphorous grenade cap on there -- so that when it hit the ground, on impact it would burst into flame and ignite the napalm. And so we used all of those things from time to time on ground ... ground attack."

Narration: MacArthur now called for the bombing of Chinese cities and for the pursuit of the war in mainland China. This was too much for Truman.

Archival Footage: President Truman

"I believe that we must try to limit the war to Korea for these vital reasons. To make sure that the precious lives of our fighting men are not wasted; to see that the security of our country and the free world is not needlessly jeopardized, and to prevent a Third World War. A number of events have made it evident that Gen. MacArthur did not agree with that policy. I have therefore considered it essential to relieve Gen. MacArthur so that there would be no doubt or confusion as to the real purpose and aim of our policy."

Narration: By the summer of 1951, the two sides had fought themselves to a stalemate in the hills of Korea -- almost at the point at which the fighting had begun a year earlier. Every month brought another 2,500 U.N. casualties.

Interview: Brig. Gen. Edwin Simmons, U.S. Marines

"It became evident to us that we were not going to fight this war to win it, that we were going to fight it to some negotiated kind of peace."

Narration: Armistice talks began in July 1951 but got nowhere. Both sides found the other's attitude impossible.

Interview: Gen. Paik Sun Yup, South Korean army

"Negotiation with the communists was very difficult. They treated the negotiations like a battlefield tactic. Something to buy time."

Narration: One of the main stumbling blocks at the truce talks was the fate of the prisoners of war. Both North and South Koreans maltreated their prisoners. One in three American POWs held by the North Koreans died during the first winter.

Interview: 'Doc' Frazier, U.S. prisoner of war

"A lot of them were lost to dysentery, diarrhea, severe beatings, malnutrition. Some of them were, you know, stragglers -- they were just ... they were just beat with rifle butts till they died, or bayoneted. Or, you either kept up or you died. It was that simple."

Narration: Concerned by the numbers dying, the Chinese took over control of the prisoners. They organized daily lectures to indoctrinate them.

Interview: 'Doc' Frazier, U.S. prisoner of war

"They would say -- 'We will tell you why you have come to Korea, why you have come thousands of miles from your home. You'll spill your blood for the profiteering warmongers on Wall Street. Why have you come here to lay down your young lives? They are sleeping with your wives and daughters. Do you think this is right?' And this would be going on for days on end, hour on end, days on end, forever -- continuously."

Narration: Back home, few people wanted to know.

Interview: Florence Galing, Army officer's wife

It wasn't like Vietnam where you ate dinner and watched television and saw the latest battle, you know. It wasn't anything like that."

Narration: In Japan, the Korean War galvanized the economy -- generating $3.5 billion dollars of spending. Japan, the ex-enemy, now became a bastion of capitalism in the struggle with communism in Asia.

Interview: Brig. Gen. Edwin Simmons, U.S. Marines

"Japan became the jumping off place for the Korean War. The dockyards and shipyards were used to rebuild, recondition the ships. Japanese electronics, which are probably now the top of the world, really got their start in the Korean War."

Narration: In South Korea, the U.N. held 130,000 communist prisoners. Each one was asked if he wanted to return to his country of origin or stay in the non-communist world. The communists were outraged when almost half of POWs chose not to return to their communist homes. Violent protest dogged the camps.

When the armistice talks resumed at Panmunjom, the fate of the prisoners delayed the negotiations for months on end.

As the truce talks stalled, the relentless bombing continued.

American bombers dropped almost as much explosive on North Korea as they had on Germany during World War II.

Interview: Yan Von Sik, North Korean army

"The bombers came without warning. Too many people died because of the bombing. You found dead people everywhere. There was hardly a single house left standing. They bombed the big cities, the villages and the countryside in the same way. I saw it all with my own eyes."

Narration: Estimates suggest that in the North as many as 2 million civilians were killed.

Interview: Ten San Din, Soviet adviser to North Korea

"It was horrific. They said Stalingrad was destroyed 96 percent in the Second World War but Pyongyang was destroyed 100 percent. Everything was burnt to ashes, not a single house left."

Narration: Throughout the war, both sides committed horrible atrocities.

Northerners killed southerners accused of sympathizing with the enemy; Rhee's supporters massacred those suspected of being communists.

In seemingly endless violence, innocent civilians were often the victims.

At Panmunjom, the talking continued.

Spanning two years, there were hundreds of meetings.

1952. Election year in America. Two years into the war, Truman decided not to run for the Democrats. The Republicans chose Dwight D Eisenhower. His slogan: 'I shall go to Korea.'

Interview: Florence Galing, Army officer's wife

"A lot of us were disenchanted with President Truman. I somehow blamed him for the war. So when the elections came up in 1952, I couldn't wait to vote for Eisenhower. I felt being a military man and his pledge was that he would see what he could do to end that war, that he was the man I wanted in office."

Narration: Eisenhower defeated the Democrats in a landslide victory.

There were changes in the east also. In March 1953, the communist world mourned the death of Stalin. Stalin had kept the war going. His successors wanted to end it.

Interview: Ten San Din, Soviet adviser to North Korea

"Soviet and North Korean leaders came to believe it was impossible to win this war. Because on the side of South Korea was the whole world and on the North Korean side was the Soviet Union and China. So an armistice was inevitable."

Narration: A cease-fire was finally agreed on July 27, 1953. The Chinese, the North Koreans and the U.N. backed the agreement. The South Korean president, Syngman Rhee, opposed the truce and refused to sign.

The massive job of exchanging prisoners of war began: 75,000 communist prisoners were handed over. 12,000 United Nations POWs were also set free.

Interview: 'Doc' Frazier, U.S. prisoner of war

"There's no words to describe how elated I was and my friends as we came across the line. It felt like tons had been lifted from your back. It felt like for the last 2 1/2 years, I'd been carrying an enormous amount of weight -- I mean tons. And all at once I could breathe, I was light. I was free. Freedom. ... Freedom's something you can't describe."

Narration: Bernie Galing also went home. Florence was there to meet him.

Interview: Florence Galing, Army officer's wife

"I had only him known him six months. We were only married six days. This young man who left with blonde wavy hair came back with brown straight hair, thinned. And he was gaunt. I mean, he no longer had the facial structure that he had when he left. This man that I had waited for, for 33 months, and then he comes home and I don't really know him. But it didn't take long."

Narration: 54,000 Americans didn't go home. The war claimed the lives of 3,000 men from the armies of 15 other nations.

In China, Mao called it a "great victory" and the Volunteers returned home as heroes. An estimated half a million Chinese soldiers had died in the war.

Interview: Chan Boliang, Chinese People's Volunteers

"The Volunteers demonstrated to the rest of the world that the Chinese were no longer the Chinese of the past. China could not be bullied. China was no longer the lame dog of Asia."

Narration: In North and South, 3 million Koreans were killed, wounded or missing. Another 5 million were homeless.

Interview: Kim Ren Ok, North Korean

"When the truce was negotiated in 1953, there was a chance for the Korean people to breathe. But there is no real victory in war. They kill so many people and destroy so much."

Narration: No victory -- but the West held the line. In Korea, communism had been contained.

Interview: Nikolai Fedorenko, Soviet Foreign Ministry

"In broad terms, it was a defeat for socialism. We were unable to impose the socialist system on South Korea, so it was a defeat."

Narration: 40 years later, at the end of the Cold War, Korea was still divided by the same line.