Many historians have argued that the Nazi attack on the Ardennes was doomed before it started, and it appears that several of Adolf Hitler’s most trusted lieutenants would have agreed. Hitler’s proposed plan (dubbed “Operation Watch on the Rhine”) hinged on an ambitious schedule that required his commanders to thrust through the Allies lines and cross the Meuse River in the span of only a few days before seizing the vital deep water port at Antwerp.

German Field Marshals Gerd von Rundstedt and Walther Model both cautioned against such an unreasonable timetable, and the pair later offered several written protests and alternative strategies, to no avail. Shortly before the attack began, Model confided to subordinates that Hitler’s plan “hasn’t got a damned leg to stand on” and “has no more than a ten percent chance of success.”

Early German gains in the Battle of the Bulge were largely due to the attack catching the Allies completely by surprise. Allied commanders often moved on intelligence gleaned by “Ultra,” a British unit that decrypted Nazi radio transmissions, but the Germans operated under a veil of secrecy and typically communicated by phone when within their own borders. Some American commanders also dismissed reports of increased German activity near the Ardennes, while others brushed off enemy prisoners who claimed that a major attack was in the offing.

Many have since claimed the Allies were blinded by their recent battlefield successes—they’d had the Germans on the defensive since D-Day—but the American high command also considered the inhospitable terrain of the Ardennes an unlikely site for a counterattack. As a result, when the German offensive finally began, the region was thinly defended by only a few exhausted and green U.S. divisions.

Few American units at the Battle of the Bulge felt the force of the German advance more severely than the 106th Golden Lions Division. The largely inexperienced outfit arrived in the Ardennes on December 11 and was ordered to cover a large section of the U.S. line in a rugged area known as Schnee Eifel. Shortly after the German attack began, the 106th’s commander, Major General Alan W. Jones, grew worried that the flanks of his 422nd and 423rd regiments were too exposed. He phoned Lieutenant General Troy Middleton to request that they be withdrawn, but the line was bad and Jones came away from the call incorrectly believing that Middleton had ordered him to keep his troops in position.

German attackers soon encircled the 422nd and 423rd and cut them off from any support. Low on ammunition and under heavy artillery fire, some 6,500 G.I.s were forced to capitulate in one of largest mass surrenders of U.S. troops during World War II. In the aftermath of the defeat, a distraught General Jones exclaimed, “I’ve lost a division faster than any other commander in the U.S. Army.”

During the early stages of the Battle of the Bulge, Hitler ordered Austrian SS commando Otto Skorzeny to assemble an army of impostors for a top-secret mission known as Operation Greif. In a now-famous ruse, Skorzeny outfitted English speaking German soldiers with captured American weapons, jeeps and uniforms and had the men slip behind the U.S. lines and pose as G.I.s. The German pretenders cut communication lines, switched road signs and committed other small acts of sabotage, but they were most successful at spreading confusion and terror.

When word got out that German commandos were masquerading as Americans, G.I.s set up checkpoints and began grilling passersby on baseball and American pop culture to confirm their identities. While they succeeded in capturing a few of the Germans, the roadblocks often produced farcical results. Overzealous American soldiers shot out the tires on British Field Marshal Bernard Montgomery’s jeep, and one G.I. even briefly detained General Omar Bradley after he answered that the capital of Illinois was Springfield (the soldier incorrectly believed it was Chicago).

The German push toward the Meuse River partially hinged on the capture of Bastogne, a small Belgian town that served as a vital road junction. The area was the scene of frantic fighting during the first few days of the battle, and by December 21, German forces had encircled town and pinned the U.S. 101st Airborne Division and others inside. Despite being heavily outnumbered, the town’s defenders responded to the siege with cheery defiance. “They’ve got us surrounded—the poor bastards!” became a refrain among the town’s G.I.s, and when the Germans later demanded commanding General Anthony McAuliffe surrender, he offered a one-word response: “Nuts!” The 101st Airborne would continue to hold Bastogne through Christmas, suffering heavy losses. The siege finally ended on December 26, when General George S. Patton’s 3rd Army punched through the German lines and relieved the city.

The U.S. military didn’t officially desegregate its ranks until 1948, but the Allies’ desperate situation during the Battle of the Bulge inspired them to turn to African American G.I.s on more than one occasion. Some 2,500 black troops participated in the engagement, with many fighting side by side with their white counterparts. The all black 333rd and 969th Field Artillery Battalions both sustained heavy casualties assisting the 101st Airborne in the defense of Bastogne, and the 969th was later awarded a Distinguished Unit Citation—the first ever presented to a black outfit.

Elsewhere on the battlefield, troops from the segregated 578th Field Artillery picked up rifles to support the 106th Golden Lions Division, and an outfit called the 761st “Black Panthers” became the first black tank unit to roll into combat under the command of General George S. Patton. As the battle wore on, Generals Dwight D. Eisenhower and John C.H. Lee called on black troops to cover the Allied losses at the front. Several thousand had volunteered by the time the engagement ended.

Along with facing down enemy gunfire and shelling, troops at the Battle of the Bulge also had to contend with the punishing climate of the Ardennes. The Nazis held off on their offensive until dense fog and snow arrived and grounded the Allies’ superior air support, leaving both sides to grapple with near-Arctic conditions. “Weather was a weapon the German army used with success,” Field Marshal Von Rundstedt later noted.

As the battle raged, blizzards and freezing rain often reduced visibility to almost zero. Frost covered much of the soldiers’ equipment, and tanks had to be chiseled out of ice after they froze to the ground overnight. Many wounded soldiers froze to death before they were rescued, and thousands of American G.I.s were eventually treated for cases of frostbite and trench foot. The skies finally shifted in the Allies’ favor on December 23, when clearing conditions allowed aircraft to take flight. The subsequent aerial barrage wreaked havoc on the German advance.

The Third Reich’s much-feared Panzer and Tiger tanks drank gas, and by late-1944, the flagging German war machine was having difficulties scrounging enough fuel to keep them running. The Nazis set aside nearly 5 million gallons for the Battle of the Bulge, yet once combat operations began, poor road conditions and logistical missteps ensured that much of the fuel never reached those who needed it. German infantry divisions resorted to using some 50,000 horses for transport in the Ardennes, and the Nazi high command built their battle plans around capturing American fuel depots during their advance. Allied forces evacuated or burned millions of gallons of gas to prevent it falling into enemy hands, however, and by Christmas many German tank units were running on fumes. With no way to continue the advance across the Meuse River, the counterattack soon crumbled. By mid-January 1945, their Allies had successfully erased the “bulge” in their lines and pushed the Germans back to their original positions.