Mel Gibson directs his first movie in a decade and—surprise—the sucker bleeds. It bleeds a lot.

As a director, Gibson stands alongside the likes of Sam Raimi, David Cronenberg and Peter Jackson as a master of body horror. Yes, I will go so far as to say his latest, Hacksaw Ridge, is an all out horror film in parts. His depiction of a World War II battle makes George Romero’s Dawn of the Dead look like Zootopia.

The movie tells the true story of Desmond Doss (Andrew Garfield), a battlefield medic and the first of three conscientious objectors in U.S. warfare history to receive the Medal of Honor. The dude refused to pick up a gun, or any weapon for that matter, during his time served in Okinawa. That didn’t stop him from braving the battlefields with comrades, eventually saving the lives of 75 men during horrendously bloody battles.

Much of the film’s first half is devoted to Doss’s backstory, a troubled childhood with his alcoholic World War I veteran father (a good Hugo Weaving) and an eventual romance with future wife Dorothy Schutte (Teresa Palmer). The early goings in the film are handled well, although they are a little schmaltzy at times. Gibson isn’t at his best when he’s handling the romance stuff.

When Doss goes to boot camp and faces off against commanding officers like Captain Glover (Sam Worthington) and Sgt. Howell (Vince Vaughn), the film starts to get very interesting. Due to his Seventh Day Adventist beliefs, Doss refuses to pick up a rifle, and this gets him into all sorts of jams on the training field and in the barracks. After a detour for a court-martial hearing, Doss and his infantry mates are deployed to Japan.

When the action switches to the scaling of the Maeda Escarpment a.k.a. Hacksaw Ridge, the movie becomes perhaps the most grueling war movie experience ever made.