Peiper's assigned route, or Rollbahn, had many hairpin turns and traversed steep hillsides that would delay his already slow-moving towed artillery and bridging trains. It included narrow, in many places single-track, roads which forced units of the Kampfgruppe to tail each other, creating a column of infantry and armor up to 25 kilometres (16 mi) long. Peiper complained that the road assigned to his Kampfgruppe was suitable for bicycles, but not for panzers. The tortuous roads prevented the Germans from concentrating their force in the blitzkrieg tactics which had served them so well in the past. Fritz Krämer, Chief of Staff for the 6th Panzer Army answered “I don’t care how and what you do. Just make it to the Meuse. Even if you’ve only one tank left when you get there.” Peiper's unit had only one-quarter the fuel they needed. Their plan counted on the capturing Allied fuel depots and keeping to an ambitious timetable.

Kampfgruppe Peiper was initially delayed by more than 16 hours when the 1st Battalion, 9th Fallschirmjger Regiment, 3rd Fallschirmjger Division took most of December 16 to defeat 18 men of the Intelligence and Reconnaissance Platoon, 394th Regiment, 99th Infantry Division who blocked the route near the tiny village of Lanzerath, Belgium in the Battle of Lanzareth ridge.

Peiper’s mechanized column did not reach his first day's objective until midnight that same day. As a result, Peiper first attacked shortly before daybreak on 17 December 1944, almost 18 hours later than expected. Hustling through the remains of the American front lines, he quickly took Honsfeld.

Peiper had planned to advance through Loseheimergroben, but the 12th and 277th Volksgrenadier Divisions failed to gain control on the first day as planned. In the early morning of December 17, they quickly captured Honsfeld and 50,000 US gallons (190,000 l; 42,000 imp gal) of fuel for his vehicles

Peiper then advanced towards Büllingen, keeping to the plan to move west, unaware he could take the town and unknowingly bypassing an opportunity to flank and trap the entire 2nd and 99th Divisions.:Peiper turned south to detour around Hünningen, interested only in getting back onto his assigned rollbahn. He continued west on his assigned rollbahn until he had to deflect shortly before Ligneuville because the assigned road was impassable. This bypass forced him towards the Baugnez crossroads where his armored units encountered a lightly armed column of U.S. artillery observers, who were quickly neutralized.

Peiper's unit became infamous for the murder of U.S. prisoners of war at the crossroads in what became known as the Malmedy massacre as noted below. Moving ahead, he crossed Ligneuville and reached the heights of Stavelot on the left bank of the Amblève River at nightfall of the second day of operation Wacht am Rhein. While the little city was defended only by a few U.S. troops and could have been easily taken the same day, for reasons unknown he held back and assaulted at dawn of the next day. Valuable time was lost, allowing the Americans to reorganise. After heavy fighting his Kampfgruppe eventually managed to cross the bridge on the River Amblève, and from there he found the going increasingly difficult.

The US forces regrouped themselves and blasted the bridges on the Amblève and the River Salm that Peiper needed to cross in order to continue on a direct road to the Meuse. On 18 December, United States Army Corps of Engineers blasted the bridges in front of him that he needed to reach his objective, trapping him in the deep valley of the Amblève, downstream from Trois-Ponts. The weather had also improved, permitting the Allied Air Forces to operate. Several P-47 squadrons attacked his column spread over 20 kilometres (12 mi). The air strikes destroyed or heavily damaged numerous vehicles of his Kampfgruppe and made some parts of his itinerary impracticable, slowing down his progression. Peiper was unable to protect his rear, which enabled American troops to recapture and destroy the bridge on the Amblève in Stavelot, cutting him off from the only possible supply road for ammunition and, above all, fuel, which he lacked. In spite of these problems, Peiper continued his progress towards Stoumont before American resistance forced him to retire to La Gleize. Short of fuel, men and ammunition he held out during six days of US Army bombardment and counterattacks. Without supplies and with no contact with other German units behind him, Peiper decided on 24 December to abandon his vehicles and march through the woods to escape. He left with the remaining 800 men and 36 hours later he reached the German lines with 770 men, having covered 20 kilometers by foot in deep snow and freezing temperatures