During World War II, the U.S. Army’s 45th Infantry Division , one of the most racially integrated units of the era, went into battle wearing on their shoulders the image of the Thunderbird , a supernatural entity said to protect humans from evil spirits and exact vengeance on their moral enemies. Composed of a disparate collection of Native Americans, Mexican Americans and Southwestern cowboys, the Thunderbird Division became known as one of the hardest-fighting combat groups of the war.

Premiering Veterans Day, a new Netflix series tells the story of this storied division as it fought across Sicily, Italy, France and into Germany. Based on the book by writer Alex Kershaw , “ The Liberator ” depicts how the Thunderbirds staggered through a withering 500-plus days of combat in less than two years, exacting a terrible toll on Axis troops while suffering nearly 10,500 casualties during the course of the war.

In addition to their impressive war experience, what set the division apart were three of its regiments—the 157th, 179th and 180th, made of young men mostly from Colorado, New Mexico, Arizona and Oklahoma— that brought Mexican Americans and at least 1,500 Native Americans from 50 tribes together as a fighting unit.

A cross between “ Band of Brothers ” and A Scanner Darkly , the four-part miniseries uses animation to tell the real-life story of Felix Sparks , a company commander who eventually rose through the division ranks, and the experiences of the fictional Sergeant Samuel Coldfoot and Corporal Able Gomez, two composite stand-ins for the Indigenous and Mexican American soldiers, respectively, who made up the bulk of the Thunderbird Division.

“The two characters are based on several of the people on my book,” says Kershaw, author of The Liberator: One World War II Soldier's 500-Day Odyssey From the Beaches of Sicily to the Gates of Dachau . “When you watch it, a lot of the time you’re looking at a Native American and a Mexican American. You’re looking at a different racial dimension to World War II.”

The series and book highlight the truly gripping and powerful drama of the 45th Division. General George S. Patton regarded the Thunderbirds as “one of the best, if not the best division in the history of American arms.”

Guy Prestia, a Pennsylvania native, joined the Thunderbird Division just before it left in 1943 for North Africa, the staging area for the invasion of Sicily. The 45th played an important role in the campaign as part of Patton’s Seventh Army, experiencing fierce resistance against the Hermann Göring Division, an elite Nazi Panzer force. Following the conquest of Sicily, Prestia took part in the amphibious landings at Salerno and Anzio on the Italian mainland. The bloody battles took the lives of many men in the Thunderbird Division as they attempted to push inland toward Rome.

In May 1944, a Choctaw sergeant named Van Barfoot singlehandedly took out three machine gun nests and captured 17 German soldiers. Later that same day, Barfoot turned back a counterattack of three Nazi Tiger tanks by destroying the lead vehicle with a bazooka. For these feats, he would be given the Congressional Medal of Honor and was also commissioned as a second lieutenant.

“I wasn’t far from him,” recalls Prestia, now a spry 98 years old. “That was near Carano in Italy. Barfoot did a lot that day.”

A few days later, Salvador J. Lara also displayed bravery that earned him the Medal of Honor. The Mexican American led his rifle squad in several assaults against German strongholds, inflicting large numbers of casualties. In one attack, Lara severely wounded his leg but would not stop until the objective was complete.

Sparks takes center stage in “The Liberator.” Awarded the Silver Star for valor, the heroic second lieutenant was one of only two men from his unit to make it back to Allied lines after being cut off by the Germans at Anzio. Later, as captain of E Company in the 157th Infantry Regiment, Sparks’ talent for leadership came through in how he treated his Mexican American subordinates. Having grown up in Arizona, Sparks witnessed firsthand the intolerance inflicted on many Latinos.

“He told me they were treated like second-class citizens and there was terrible discrimination,” Kershaw says. “Before Sparks went into combat in Salerno, he was worried. Are they going to die for a country that treats them that way? After the first day of battle, he was so proud because they were fantastic soldiers.”

After Italy, the 45th Division went to France, where it participated in its fourth amphibious landing of the war at St. Maxime. The Thunderbirds continued to push the Germans back to their own border while liberating numerous towns and cities and breaching the Maginot Line .

The 45th broke through the Siegfried Line and entered Germany in March 1945. The unit fought in the battles of Aschaffenburg and Nuremburg, then was ordered at the end of April to make a bee-line for Berchtesgaden with hopes of capturing Nazi leader Adolf Hitler at his Alpine retreat. Along the way, the unit was ordered to make a detour to a place called Dachau .

“We didn’t know what that was,” says 95-year-old Dan Dougherty, who joined the Thunderbirds just after the Battle of the Bulge. “We hadn’t been told about concentration camps. The only thing they warned us about was lice.”

“Going in was the terrible experience,” he recalls. “We came along a long train of boxcars, full of emaciated corpses. It just blew everybody away.”

It was at Dachau that Sparks, then a lieutenant colonel, truly became a legend to the troops. They already loved him for his compassion and his fierceness as a leader. However, they worshiped him after he stood up to a superior officer for assaulting a soldier.

Major General Henning Linden led the 42nd Division into Dachau at about the same time as Sparks did as commander of 3rd Battalion with the 157th Regiment. When the two units met inside the large camp, Linden tried to take control of the situation—and grab the headlines as liberator. Sparks was having none of it, and told his superior officer that he was under orders to seal off his portion of the concentration camp. The lieutenant colonel then ordered a private to escort the general out of their zone.

“Linden took his riding crop and wacked the private on the helmet,” Kershaw says. “Sparks told me it wasn’t hard but he snapped. He pulled out his pistol, pointed it at the general’s head and said, ‘You touch another one of my men and I will (expletive) kill you right here right now.’ He was a god to his men after that.”

Sparks was eventually relieved of command of his battalion, though by that time, the war was nearly over and the serious fighting was all but finished. Sparks would later go to college under the G.I. Bill and become a lawyer, eventually serving as a Colorado Supreme Court Justice.

Sparks, who died in 2007, was deeply moved by his time with the Thunderbirds. He became an advocate for civil rights and spoke out frequently against racism of any kind. He also stood up to Holocaust deniers and angrily told them what he witnessed.

“I hero-worship this man like no one else from World War II,” Kershaw says. “I admire and respect his toughness, his resilience, his spirit, his love, his huge humanity, his compassion. He was a working-class American hero like I have never before in my life come across. He was a kickass warrior who led Mexican Americans, Native Americans, poor cowboys, kids that had nothing. He turned them into an amazing fighting team that defeated Nazism.”

Prestia was also impressed by Sparks’ concern for others, especially the soldiers under his command. He recalls one incident in France when the battalion commander put his life on the line for his men. Several soldiers had been wounded by the Germans and Sparks went into the line of fire to get them.

“He was in the open,” Prestia recalls. “Across the field there was a machine gun nest set up. They had him right in their sights. The German commander told his gunners, ‘Don’t you fire on that man. Anybody who has that kind of courage to pull his soldiers to safety, you don’t shoot anybody like that.’”

Like the Thunderbird, the Liberator himself was a force for good against the spirits of evil.