On June 25, 1950 eighty-nine thousand soldiers of the North Korean People’s Army launched a devastating surprise attack on South Korea. Well equipped with Soviet-supplied tanks, artillery and automatic weapons, they swiftly overran defending South Korean troops that numbered less than half their number and seized the capital of Seoul in just three days.

U.S. president Harry Truman managed to get to the United Nations to mobilize militarily against the invasion—a move only made possible due to a then-ongoing Soviet boycott.

However, intervention by UN troops would mean little if the entire Korean Peninsula was captured before the weeks it would take for them to arrive, as seemed likely. U.S. fighter planes based in Japan and on aircraft carriers soon joined the fray. However, the closest ground unit with any chance of making it in time lay just across the Tsushima Strait: the Twenty-Fourth Infantry Division, then deployed in the American occupation of Japan.

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Despite emerging from World War II with a triumphant reputation, the Army had been hollowed out in the postwar years. In the early phase of the new era of atomic warfare, it was expected that nuclear weapons would do all the killing, and troops on the ground would simply mop up what was left and guard nuclear-weapons facilities. While the Pentagon focused on strategic bombers, the Army did not even standardize equipment upgrades that it had devised by the end of World War II, such as standardizing the issue of the M26 Pershing tank and the 3.5-inch M20 Super Bazooka for the infantry.

The Twenty-Fourth Division in particular was composed largely of draftees with only two months of basic training, and was still equipped with older World War II–era support weapons. The divisional commander Maj. Gen. William Dean assigned Lt. Col. Charles Smith, a veteran of the Battle of Guadalcanal, to command the lead battalion to deploy into Korea. Butler planned on deploying the bulk of the Twenty-Fourth Division to defend the city of Taejon, but he wanted Smith to race ahead “as far north as possible” to delay the North Korean advance.

Task Force Smith was composed of the understrength First Battalion of the Twenty-First Infantry regiment; with 406 men, it had only two out of the standard three infantry companies. For heavy weapons, it had only a half dozen mortars and 2.36-inch bazookas each, as well as a couple seventy-five-millimeter recoilless rifles. Artillery support was provided by six 105-millimeter howitzers from A Battery of the Fifty-Second Field Artillery battalion, which counted an additional 134 men.

Smith’s battalion was airlifted to Korea on July 1, and by Independence Day he had raced his troops all the way to the village of Osan, southeast of Seoul. Just north of the village he dug his infantry in on two ninety-meter-high hills overlooking a road leading to Taejon, stretched out along a mile-long defensive line. He situated five howitzers a mile to the rear to provide fire support, while he deployed the number-six gun farther west, to pick off any vehicles passing between the two hills. You can see a map of his deployment here.

At 7:30 a.m. the following morning—July 5—the American GIs spotted a company of eight T-34/85 tanks of the 107th Tank Regiment racing down the highway towards them. During World War II, the T-34 had played a vital role in the defense of the Soviet Union from German panzers, boasting a useful combination of mobility, protection and firepower. An upgrade to a eighty-five-millimeter gun by 1944 kept the vehicle technologically viable through the end of the war and beyond.

At a quarter past eight, the howitzers began blasting the tanks with high-explosive shells from a mile away, beginning the first engagement by U.S. ground forces in the Korean War. Soon the seventy-five-millimeter recoilless rifles joined the bombardment. The T-34 crews remained buttoned inside their tanks—unable to spot the American forces well, but also largely unaffected by the shrapnel shredding the air around them.

U.S. infantry waited until the lead tank had rolled up to only a dozen yards from their bazookas—and then struck the Soviet-made tanks with no fewer than twenty-two antitank rockets. Apparently unaffected, the North Korean tankers simply rolled straight through the “roadblock,” not finding the infantry worth their time to stop and engage.

Both the old M9A1 bazooka and M20 recoilless rifle could theoretically only barely pierce the T-34’s one hundred millimeters of front armor with their shaped-charge warheads. However, because hits to the weaker side armor also failed to penetrate, it seems likely the warheads were defective. Furthermore, the howitzers’ 105-millimeter high-explosive rounds, though powerful, were not designed for armor penetration.

As the tanks charged towards the howitzers, they ran into a carefully laid ambush: the artillerymen did possess exactly six High Explosive Anti-Tank rounds—reportedly, one third of the supply then available to U.S. forces in all of Asia! These were all allocated to the number-six gun of Corporal Herman Critchfield, who managed to disable two tanks at short range.

One of the T-34s brewed up in flames, and its dismounting crewmembers sprayed a nearby machine-gun position with his burp gun, causing the first death of an American soldier in Korea. Shellfire from the T-34s blew up most of the infantry’s trucks, knocked out Critchfield’s gun and wounded the battery’s commanding officer, Capt. Miller Perry. A third tank was immobilized by a hit to its treads, while the five remaining tanks eventually continued down the road to Taejon.

Task Force Smith’s misfortunes had only just begun. An hour later, another twenty-five tanks came barreling towards their position. Howitzer fire managed to immobilize another tank and damage a few more, but the rest got through and personnel from the demoralized battery nearly fled from the field before being rallied by Captain Perry.

Then, at 11 a.m., a six-mile long column of North Korean trucks from the Sixteenth and Eighteenth Infantry Regiments escorted by three tanks advanced on Smith’s position, oblivious to the skirmishes that had taken place earlier that morning. Once they had closed within a thousand yards, the American troops opened fire with mortars, machine guns and howitzers, spreading chaos through the column.

However, Smith’s force was outnumbered ten to one by the more than five thousand North Korean troops. Under command of Gen. Lee Kwon-mu, the Communist infantry spread out to envelope the isolated roadblock from both ends. After three hours of fighting, Smith decided he would have to withdraw to avoid losing his entire force.

Unfortunately, the passing tanks had crushed Smith’s communication lines, and word of his planned orderly withdrawal did not make it to all the troops. One platoon only found out at the last moment, and left its wounded soldiers behind in its haste to escape. They were later found to have been murdered in their stretchers.

The retreat exposed the American infantry in the open to enemy fire, and as Korean machine-gun and shell fire raked their positions, panic set in. The controlled retreat disintegrated into a pell-mell route. The howitzer crews at least managed to spike the sights on their howitzers before roaring away in their truck, picking up stragglers here and there as they went.

Ultimately, Task Force Smith lost over a third of its strength: sixty men killed in action, another twenty-one wounded and eighty-two captured (only fifty of whom survived the war). The survivors straggled back to American lines over the course of several days, linking up with the defenses established by the rest of the Twenty-Fourth Infantry Division. Historians estimate the inexperienced troops had bought U.S. forces in Korea seven vital hours.

However, things did not improve much from there. Despite quickly winning air superiority, U.S. and South Korean troops suffered defeat after defeat on the ground over the next two months until they were confined to a small defensive perimeter around the southeastern port city of Pusan. The first M24 light tanks to enter action were outgunned by the T-34s, while World War II–vintage Shermans were at best only evenly matched. Only in September did a surprise amphibious assault at Inchon, west of Seoul, reverse UN fortunes in the theater by cutting North Korean supply lines.

The debacle of Task Force Smith is relatively well documented, and has become a byword in the Army for the risk that rapid-response troops hastily inserted into a crisis situation may run, by lacking the necessary firepower to defend themselves.

Could a similar situation occur today? In the Korean theater this is unlikely, as the South Korean army has grown dramatically in capability, and defenses along the demilitarized zone are very well developed. Of course, the U.S. military has also greatly improved its technological advantage vis-à-vis potential adversaries, and can field highly portable Javelin antitank weapons and more precise air-to-ground weapons.