It's hard to believe how heroic Desmond Doss was. So hard, 'Hacksaw Ridge' director Mel Gibson and producers left some of it out.

Most movie adaptations of true stories exaggerate for effect, condensing timelines and adding action to heighten drama. In “Hacksaw Ridge,” the story of a World War II conscientious objector who was awarded the Medal of Honor for his heroic duty as a medic, director Mel Gibson and producers had the opposite problem.

“There were things that left us thinking ‘Who would believe that?’” producer Bill Mechanic told “Deadline.”

Gibson’s long and bumpy path to directing again ended in a standing ovation for “Hacksaw Ridge” at the Venice Film Festival in 2016. On a budget and shooting schedule roughly half of what he used for “Braveheart” 20 years ago, Gibson brought to life the story of Cpl. Desmond Doss, a Seventh-Day Adventist whose heroics at Okinawa in the waning days of World War II saved 75 men, all while under heavy enemy fire. While honoring a religious conviction to never pick up a weapon, Doss served as a medic as American troops attempted to take a strategically vital 400-foot cliff nicknamed Hacksaw Ridge for its unforgiving terrain and deadly reputation.

“Here you make a film about a real superhero, a guy who really existed and really did super heroic things…but as an ordinary man, it’s hard to find the funds,” Gibson told the website Collider, lamenting the preponderance of spandex-clad superheroes in Hollywood.

As you might expect from a Gibson portrayal of World War II, “Hacksaw Ridge” is heavy on realism, delivering more gritty detail than some can handle of the Japanese assault on American soldiers as they crested the cliff.

“I thought it was important to make it brutal and give the audience a modicum or taste of understanding of what it was like to be in a foxhole in that place,” Gibson told Collider. “So that they could better appreciate not only what our veterans have sacrificed and go through for our freedoms, but to juxtapose that against what Desmond Doss was…It was a landscape of death and this man reaffirms life in the midst of all that sort of state, like a flower growing in the wasteland.”

A tender and nuanced performance by British actor Andrew Garfield as Doss has earned Oscar buzz. He prevents the first half of the film, spent on the hero’s upbringing in Lynchburg, Va., from being overly saccharine and the second half from sinking under the weight of its violence. (Plus, his Southern accent is decent, a rare Hollywood achievement!)

But Doss’ life and combat performance are even more astounding than the film relates. The movie mostly covers the events of the battle for the ridge while Doss’ Medal of Honor citation includes his exploits over a period of three weeks in Okinawa, in April and May of 1944. During that one battle, Doss is credited with saving 75 men, going back into enemy fire without a weapon again and again over a 12-hour period, carrying the wounded over the battleground without cover, and lowering them with an improvised rope litter system down the sheer face of the cliff one by one. Doss himself contended he only saved 50, but his officers claimed 100, so they settled on 75.

Here are five other amazing things he did.

1. He Waited For Aid for Five Hours After Being Wounded By a Grenade

“Hacksaw Ridge” takes liberties with the timing of Doss’ wounding at Okinawa, putting his run-in with an enemy grenade atop the infamous escarpment when it really happened later that month in another battle. Doss had worked through the night in an exposed area, treating the wounded, according to his Medal of Honor citation.

“They begin to throw these hand grenades,” Doss said in the 2004 documentary, “Conscientious Objector.” “I saw it comin’. There was three other men in the hole with me. They were on the lower side, but I was on the other side lookin’ when they threw the thing. I knew there was no way I could get at it. So I just quickly took my left foot and threw it back to where I thought the grenade might be, and throw my head and helmet to the ground. And not more than half a second later, I felt like I was sailin’ through the air. I was seein’ stars I wasn’t supposed to be seein’, and I knew my legs and body were blown up.”

He got 17 pieces of shrapnel in his leg trying to protect other men from the explosive. Instead of “call(ing) another aid man from cover, he cared for his own injuries and waited 5 hours before litter bearers reached him and started carrying him to cover,” according to his citation.

2. He Then Gave Up His Litter for Another Man

When help finally came, as they were leaving the battlefield Doss saw “a more critically wounded man nearby” and rolled off the litter to treat him and direct his rescuers to do the same, then gave his litter to the wounded man, sentencing himself to another long wait for help.

3. He Crawled 300 Yards to Safety With a Compound Fracture After Being Hit By a Sniper

While Doss was waiting the second time, a sniper’s bullet shattered his arm.

“With magnificent fortitude he bound a rifle stock to his shattered arm as a splint and then crawled 300 yards over rough terrain to the aid station,” according to his Medal of Honor citation.

4. He Did All Of This Despite A Serious Childhood Injury to One of His Hands

As a child, Doss fell on a broken bottle and cut his hand across the palm, slicing several tendons, according to his biography, “Redemption at Hacksaw Ridge” by Booton Herndon. A doctor told him at eight he’d never use the hand again, but his mother helped him rehab it for months to regain the use of his fingers. He never played baseball again, but he did rescue 75 men.

5. Despite His War Injuries, He Rescued 9 From a Cave in Georgia in 1966

During his time in the Pacific Theater, Doss was injured twice and contracted tuberculosis. After the war, he was classified as 90-percent disabled and did five years of treatment, during which he lost five ribs and a lung to the disease. His affliction was especially heartbreaking because it limited the contact he could have with his son, Desmond “Tommy” Doss Jr., according to his 1967 biography. Nonetheless, Doss continued farming his land in North Georgia with his wife Dorothy and stayed involved in his community and church. He led his local division of the Civilian Defense rescue service, raising money for the unit’s truck and outfitting it for duty.

Twenty years after the war, Doss’ rescue skills were put to the test again in rural Georgia: “Eight boy scouts and three adult leaders became lost in a cave. Working around the clock in the dark, wet, gas-filled cavern, Desmond and his co-workers saved seven of the scouts and one of the leaders. After it was all over the other rescue workers revealed that Desmond spent more consecutive hours in the cave working harder than anyone else.”

Many of the stories of the Greatest Generation make one marvel at the astounding men and women of that time and the astounding things the world asked of them. This is true of Desmond Doss’ story— so true the movie had to leave some of it out to make us believe it.