Saving Private Ryan: the meat-grinder of the D-Day landings: the traumatic chaos and helplessness in the face of extreme violence. In fact the opening played down what a nightmare the Omaha Beach landing was by showing it being over relatively quickly. Extend that scene out to a day if you want to imagine the real thing. Also, that was after the defense was fooled in moving more than half of their forces away. Imagine how a full frontal assault would have gone down!
Black Hawk Down: A war where the people you are nominally fighting for are also the enemy: the experience of fighting an unwinnable war. Also see War Is Glorious, for the other side of the story.
Das Boot: Set in 1942, follows the story of a real life submarine and its crew. Few movies manage to convey a sense of terror, futility and frustration all at once and with such skill.
The Thin Red Line: American soldiers faced with the brutality of the World War II Japanese military struggling not to commit retaliatory war crimes. Lots of Gray and Gray Morality, honest Tear Jerker moments and serious contemplation about whether war is an inevitable part of human civilization or not.
Platoon. Set in Vietnam, this movie does not attempt balance: it is an all-out War Is Hell work. It contains war crimes including murder and attempted rape, graphic imagery of violent death and maiming, PTSD, drug use, mistaken fire on friendly units, and focuses on lethal infighting. note For the record, the drug use was generally one of the more positive elements the protagonist encountered.
The Deer Hunter. Hellish experience while in Vietnam. Shell shock when returning. And then gets even worse for the attempted rescue of one who got left behind. Given to their experiences in war, even work at Steel Mill feels a leisurely activity.
Even Operation Dumbo Drop has this as it portrays the hypocrisy of the US Army's "Hearts and Minds" campaign (they try to win civilian support only when it suits them) and how the average civilian doesn't really care who wins the war.
Lord of War: Those who suffer in war are rarely those who benefit and conflict need not be just. The special horror of feeding murder and destruction for monetary gain.
Gallipoli: exuberant and naive boys from outback Australia go to war. Their illusions are shattered in the botched assault landings at Gallipoli.
The Russian film Come and See is about a little boy turned partisan during World War II. It ends in insanity and shows incredible cruelty on both sides. The title itself is a reference to the biblical Apocalypse.
Another good example: Purgatory (Chistilishe in Russian). Is about first Chechen war. Takes violence to a whole new level.
The Guns of Navarone. Every win comes at a price. The line which separates right and wrong becomes very blurry in pursuit of victory. After the team escapes captivity, the Nazis torch the village of Mandrakos. Imagine what they will do to every village in Navarone now that the guns are destroyed. Finally, Butcher Brown suffers Post Traumatic Stress Disorder after his combat in the Spanish Civil War.
Zhang Yimou's Red Sorghum shows the effect of the Second Sino-Japanese War note part of World War II on one man's family; focusing on the narrator's grandmother's sorghum-liquor distillery.
Zhang Yimou's To Live: the main characters, touring China with a traditional Chinese shadow-puppet troupe, are impressed into the Nationalist army during the Chinese Civil War. They fall asleep one night and wake up to find that a battle has taken place; the field is strewn with bodies, most of them Nationalist, and their friend's brother's body is found among the carnage. They surrender to the advancing Communists, who have them enlist when they find that their new captives can entertain them with shadow puppets.
Hunter and Ramsey discuss the theories and philosophy of Von Clausewitz over dinner in Crimson Tide. Hunter comes to the conclusion not that War is Hell, but that War is Doom. note He must have been keeping these opinions to himself up until now: the U.S Navy isn't that keen on pacifist officers. Still, the psychological toll on the crew of the imminence of nuclear launch (and the ramifications thereof), of damage taken, and the known presence but unknown location of enemy attack submarines is clearly portrayed.
Hunter:In my humble opinion, in the nuclear world, the true enemy is war itself.
Die Brücke. During the final days of WW 2, a number of freshly-drafted and (at first) still enthusiastic German kids fight and die one by one in order to hold an ultimately irrelevant bridge against the American advance.
The pair of movies Flags of Our Fathers and Letters from Iwo Jima show this viewpoint when taken together. Both movies present war fairly honestly from each sides' perspective and could be taken to glorify war individually. However, watching a movie where you sympathize with the characters and their motivations on one side of the most bloody and desperate battles in World War II, then watch a movie where you sympathize with characters and their motivations on the other side of the same combat, and realize that there is no possible way things can turn out better for one group without terrible, terrible things having happened to the other... well that is pretty effective.
Cross Of Iron; a squad of war weary German veterans are on the eastern front in 1943.
Waltz with Bashir : Two Israeli ex-soldiers sit in an inn and reflect on their experiences in the first Lebanon war. Folman is so traumatized he has forgotten everything and over the course of the movie he speaks to others who were there and finds out what happened...
All Quiet on the Western Front is a famous war film set in WWI about several German graduates who naively choose to go to war only to find a world of brutal training and pointless death. It is also considered one of the greatest films ever made, and one of the anti war films ever made, if not the best. The fight scenes are so realistic that they are still being used in documentaries about WWI to this day.
The Animatrix two-part short, "The Second Renaissance", chillingly blends this with And Man Grew Proud. Some scenes from that movie prompt shivers. Not every war is between equal forces — there is a special horror to being hopelessly outgunned. The human forces desperate sacrifice is futile and bloody. The death scenes evoke mechanised warfare in raw grisly essence.
Jarhead: Just sitting in a desert waiting for war to begin is already hell. The fact that it never does for some is absolutely soul crushing and leaves soldiers battling lingering feelings of despair, loneliness, and alienation instead of an enemy on the battlefield.
When Trumpets Fade, about the battle of Hürtgen Forest in the autumn of 1944 - a senseless hell of fog, snow, land mines and shrapnel in which suicidal missions are the only way to break the deadlock.
Then the Battle of the Bulge began a couple of weeks later which overshadowed this conflict.
The Good The Bad And The Ugly: The American Civil War is integral to the fabric of the film, and Leone is here to serve it up raw. It is remarkable that film known primarily as a classic Western would use this as a core theme. Tattered armies in retreat. Exhausted, demoralized drunken commanders, chaos, dirt and unregarded bodies in the sun. Corn cobs to eat, scabrous prison camps, and summary justice meted out on the streets. The POW camp commander mentions Andersonville Prison, a hell-on-Earth death camp. He also berates Angel Eyes for the organized bleeding of money from prisoners. The trope is perhaps most strongly in play during the futile fight for a bridge that Blondie and Tuco witness. An unremarked mass of shallow war graves make up the film's final setting.
The Polish film Ashes and Diamonds: Alliances not built on trust will quickly crumble. Another war begins just as another ends.
Zulu. "Do you think I could stand this butcher's yard more than once?"
The film does, however, adhere to the 60s trope of bloodless wounds - including bayonettings. The actual Zulu practice of disemboweling the dead, much referred to in accounts of the Isandlwana battlefield is also not referred to; the British troops found this quite revolting but it was described by the Zulu as a religious rite, allowing the soul of the dead man to escape and not haunt his killer. YMMV on the accuracy of this.
How I Won the War seems very comical and satirical, but it has a particularly brutal underbelly. It's viewed and monologued by the Kilgore, however, and manages to at first glance come off as War Is Glorious, at least until you remember he got the rest of his men killed with poorly planned actions, and generally bad training. Mostly a shot at careerist military men who would do anything for a promotion or a medal, as well as being generally incompetent on all fronts, and how costly such a thing is to everyone but them. Without selling or stealing a single physical tangible thing it is still easy to classify Lieutenant Goodbody as a 'war profiteer,' as there is no doubt from the conversations he has with his German counterpart he will no doubt go on to write a best-seller about his 'heroism under fire' and being the sole survivor of his squad.
The Patriot: Benjamin Martin helps win the war but his home is destroyed, two of his sons are dead and the other two are forced to kill at a young age, irreversibly changing them both (one is scarred for life, the other likes it too much).
In A Very Long Engagement a young, cheerful man is conscripted from his simple and happy country life to fight in World War One. After seeing too much misery he decides to self-mutilate in an attempt to get sent home, but his superior won't allow it, and his superior tears up the pardon. So he's sent in the no-man's area between the two warring factions, gets shot up and ends up so traumatized he loses his memory. The whole film is interspersed with brutally realistic scenes intended to depict the hell of war even more powerfully.
While The Enemy Below is more a straight war-adventure-suspense story, it does touch on the aspects: Captain Murrell lost his British wife to a u-boat when he was trying to evacuate her from Britain on his ship when he was a merchant mariner. Von Stolberg has lost his son in battle, and doubts he's on the right side of the war. The two of them—honorable, intelligent, and compassionate men who respect each other's abilities—spend most of the film trying to kill each other.
Played straight in War Horse, with the war being hell for horses and men alike.
Gettysburg: Depicting a battle in which over 50,000 men were killed or wounded over three days. The 20th Maine started with 1,000 men and has been cut down to 300 because the Union is just using them until there's no one left. Bodies carpet the battlefield and medical treatment is almost as dangerous as going into battle in the first place. Old friends who are like brothers are forced to fight each other, and Pickett's Charge is a hideous mistake that leaves ten thousand men dead on the field.
The Crossing: The Darkest Hour for the Continental army. It's cold, wet winter, men are forced to march while sick and wounded and shoeless, thoroughly trounced and dispirited by their failures against the British army. The fighting is brutal and bloody to the degree that you wince on behalf of the Hessians, even knowing that some of these men shot down Washington's own troops when they tried to surrender.