War is usually glorified in today’s United States, often celebrated. We praise all our men and women in uniform as being “heroes.” But in the America of 1950, U.S. soldiers and marines who fought the opening salvos of the Korean War knew full well that war—real war—is nothing to celebrate, but something to avoid at all costs.

On June 25, 1950, Communist North Korea, under the leadership of dictator Kim Il-sung (grandfather of current North Korean dictator Kim Jong-un), launched a no-notice and unprovoked war against South Korea. When the invasion started, the U.S. military presence on the peninsula consisted of a handful of military trainers assigned to the Korean Military Assistance Group (KMAG).

World War II, which had inflicted approximate sixty million deaths on the globe, had ended five years earlier. Americans, both military leaders and civilians, were sick of war, wanted nothing to do with another one, and thought it would be many years into the future before another would be possible.

As a result, most army and marine units were barely at 50 percent strength, and few did any real combat training. Most of the combat veterans had been discharged, leaving the ranks filled by mostly inexperienced, untrained and poorly disciplined troops. The initial cost of this unpreparedness would be devastating.

President Harry Truman signed an order sending U.S. troops to the defense of South Korea on June 27, 1950. The first unit to arrive was called Task Force Smith, a battalion-sized group of 406 men, from the 24th Infantry Division, stationed in Japan at the time. On July 5, they were sent into action south of Osan to halt the North Korean armored advance.

U.S. leaders expected the North Koreans would stop in fear once they realized that American combat forces had entered the war. Instead, Task Force Smith was utterly routed, reportedly slowing the Communist advance by a mere six hours, losing approximately 180 men in the process.

Stunned at the speed of the defeat, U.S. leaders scrambled to get more combat power into Korea as soon as possible, fearing that if it took too long, North Korea might capture the whole of the peninsula, expanding communist control in the Asia-Pacific region. The remainder of the 24th Division was rushed in south of Osan, and between July 14–21 fought and lost against the North Korean People’s Army (NKPA) at the Battle of Taejon. Their loss, however, allowed the United States to rush additional soldiers and marines still further south in an attempt to stop the North Koreans.

By early August, the 24th Division, now at barely 40 percent strength, set up defensive positions in what would later be known as the Pusan Perimeter—a relatively small patch of land 140 miles across on the southeastern tip of the peninsula; North Korea occupied everything else. More U.S. and allied troops were streaming into the port city of Pusan, but unless the 24th Division and newly-arrived 5th Marine Regiment, later to become known as the Fire Brigade, could hold the western part of the perimeter, the war might be lost.

Too often, many in America today hear the term “war” and don’t have a good understanding for what it actually means on the ground. The remnants of the 24th Infantry and the fresh 5th Marines eventually overcame the North Korean onslaught and with Gen. Douglas MacArthur’s famous Inchon Landings in September, the southern part of the peninsula was eventually saved. But the cost to the American troops was nightmarish and horrifying; difficult to fathom now sixty-seven years later.

To give a brief but representative glimpse of what the fighting was like for the U.S. troops, I will share excerpts from the experience one soldier, fighting in what became known as the Naktong Bulge. 1st Lt. Frank Munoz, from the 24th Division led troops in the most intense part of the fighting.

As described in vivid detail in T. R. Fehrenbach’s classic history of the Korean War “This Kind of War,” Munoz became commander of an infantry company because of battlefield losses. His experience shows the brutish, horrific nature of war. It was neither pretty nor clean. In one engagement, Munoz had disabled a NKPA T-34 tank but didn’t have any more anti-tank ammunition and thus couldn’t kill the troops inside the tank. A fellow officer, 1st Lt. Edward Schmitt, arrived on the scene and when told of the surviving crew inside, he became incensed and began shouting at them to surrender.

Getting no response, he climbed up on the tank and began to open the hatch. The crew inside thrust a pistol out and tried to shoot him—but missed. Fehrenbach wrote that Schmitt screamed, “‘You son of a bitch, we’ll fix you!’ he said. ‘Somebody give me a white phosphorous grenade.’ Pulling the pin, Schmitt dropped the incendiary grenade on the tank’s back deck, over the air intake. The North Koreans never did come out, though they made a number of unpleasant noises as they stayed inside and burned.”

Relieved of the threat to his rear, Munoz returned to face the threat to his front. He was ordered to take a key hill, necessary for the defense of that part of the perimeter. Once he arrived at the crest of the hill, suffering the loss of more than half his men in the process, Fehrenbach writes that Munoz suddenly “made eyeball to eyeball contact with a North Korean soldier. Munoz moved first. His .45 slug killed the Korean at a range of inches. As he shot, he could see two waves of enemy infantry, bayonets fixed, charging up the slope firing from the hip.”

The onslaught was too much for two of his men, who mentally broke, got out of their foxholes and ran for the rear. Both were shot in the back by advancing North Koreans. Munoz knew that they would not survive on their own. To save him and his men, he ordered a massive artillery strike to be fired on his positions. At first the artillery officer refused, not wanting to kill Americans. Munoz was relentless, however, and the barrage was fired. Because the U.S. troops were in their foxholes, the exploding shells ripped apart the NKPA soldiers but didn’t kill any Americans.

The U.S. and allied troops later turned the tide of the North Korean advance and eventually pushed them to the border with China—at which time more than 300,000 Chinese soldiers entered the war to defend North Korea. The fighting eventually settled into a stalemate about mid-way down the peninsula, and an armistice ended the war in 1953. The United States suffered more than 36,000 killed and 103,000 wounded—a very expensive bill to earn a stalemate.

As the situation continues to heat up on the Korean Peninsula today, American policymakers and people should keep in mind that if a new war should break out there, the cost would be profoundly higher, as the population of South Korea is 30 million larger today than in 1950, and the weapons of war far, far more lethal. The human suffering and costs to U.S. troops, should they fight there, would be incalculable. Before any such action is taken, U.S., South Korean, Japanese, and even Chinese and Russian leaders need to be absolutely certain that any gains made from war would be worth the terrifying costs. We must never again sacrifice so much for so little gain.

Daniel L. Davis is a Senior Fellow for Defense Priorities and a former Lt. Col. in the U.S. Army who retired in 2015 after 21 years, including four combat deployments and a tour of duty in South Korea. Follow him @DanielLDavis1.

Image: People cheer as a missile is driven past the stand with North Korean leader Kim Jong Un and other high ranking officials during a military parade marking the 105th birth anniversary of country's founding father Kim Il Sung, in Pyongyang April 15, 2017. REUTERS/Damir Sagolj