Mike Colalillo, who was awarded the Medal of Honor for an extraordinary machine gun assault on German soldiers toward the end of World War II that inflicted 25 enemy casualties, died Dec. 30 at a nursing facility in Duluth, Minn. He was 86.

He had congestive heart failure, said his son, Al Colalillo.

On April 7, 1945, Mr. Colalillo was a 19-year-old Army private first class on a patrol outside Untergriesheim, Germany, when his unit came under a barrage of enemy fire.

Pinned down by German machine guns and artillery, Mr. Colalillo turned to his fellow soldiers and told them to follow his lead. Inspired by his confidence, the soldiers “advanced in the face of savage enemy fire,” according to his citationfor the Medal of Honor, the military’s highest award for valor.

Mr. Colalillo surged toward the Germans, firing his submachine gun until it was knocked from his hands by shrapnel. He then ran toward an American tank to take control of a machine gun mounted above its cannon turret.

Bullets clanged off the tank’s armor and zipped by his body as Mr. Colalillo delivered his own withering response to the German onslaught.

“It was a rough time, and I was scared,” Mr. Colalillo told the St. Paul Pioneer Press in 2004, “but I had to do what I had to do.”

Mr. Colalillo blasted at one enemy position “with such devastating accuracy,” the Medal of Honor citation read, that he killed or wounded at least 10 German soldiers and silenced a machine gun nest.

He continued his counterattack, directing his fire toward other German positions, killing another three Germans and destroying another machine gun position. After his gun jammed, Mr. Colalillo dismounted from the tank and grabbed a submachine gun to continue his assault on foot. According to the Medal of Honor citation, he killed or wounded 25 enemy soldiers.

When ordered to withdraw, Mr. Colalillo stayed behind to carry a wounded soldier over his shoulder through open terrain while artillery and mortar rounds pulverized the ground around him.

A few weeks later, he was approached by two military police officers who escorted him to a nearby headquarters. He recalled later that he thought he was under arrest. He was informed that the tank’s commander had nominated him for the Medal of Honor, which he received in December 1945 at a White House ceremony.

Mr. Colalillo said his boyhood friends in Minnesota were surprised by the award and told him, “How could a little twerp like you get the Medal of Honor?”

Michael Colalillo was born Dec. 1, 1925, in Hibbing, Minn., and grew up in West Duluth. His parents were Italian immigrants and had nine children.

After his mother died, he dropped out of school at 16 to support the family. He worked in a bakery where he said he “did everything from cleaning pans to putting jelly in the Bismarcks,” a type of pastry.

After his military service, Mr. Colalillo worked for an ironworks and was seriously injured on the job when one of his arms got caught in a conveyor belt. He never fully recovered. He later was a foreman at a warehouse near the Duluth harbor and retired in the late 1980s.

His wife of 61 years, Lina Nissila Colalillo, died in 2007. Their daughter Joanne Colalillo died in 2001.

Survivors include two children, Al Colalillo of Hayward, Wis., and Michele Schneeberger of Meadowlands, Minn.; a brother; two sisters; two grandsons; and three great-grandchildren.