Shutter Island explained

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What is Shutter Island about?

Shutter Island initially presents itself as a cautionary tale about paranoia relating to government, psychology, and the powers that be. That all changes once you realize that Teddy Daniels really is Andrew Laeddis, has been a psych patient at Ashecliffe for the past 24 months, and is in extreme and aggressive denial about what happened to his wife, Dolores, and their kids. At the end of the movie, right before the lobotomy, Shutter Island reveals its true thesis. This happens when Teddy asks Dr. Sheehan (aka, Chuck), “Which would be worse? To live as a monster or die as a good man?”

That moment is meaningful as it’s a break from the delusional script that Sheehan and Dr. Cawley clearly know very well. Which is why Sheehan reacts with such surprise, saying, “Teddy?” with a questioning tone. This is Shutter Island indicating to the viewer we need to think about who is present in that moment. Teddy or Andrew. 

Teddy is the delusional and volatile persona created by Laeddis as a defense mechanism to escape the pain of knowing he murdered his wife after she annihilated their kids. Andrew is the smart, decent, good person who can’t handle the guilt and pain of knowing what he lost. 

Once we’re clear that there’s no sinister mystery, that Teddy wasn’t tricked by the people at Ashecliffe to believe he’s Andrew, that the true twist is very simple and sad, we can easily explain the remaining questions. 

Movie Guide table of contents

Cast

• Edward Daniels/Andrew Laeddis – Leonardo DiCaprio
• Dolores Chanal – Michelle Williams
• Chuck Aule/Dr. Sheehan – Mark Ruffalo
• Dr. Cawley – Ben Kingsley
• Dr. Naehring – Max von Sydow
• Deputy Warden – John Carroll Lynch
• Rachel Solando – Emily Mortimer
• Rachel in cave – Patricia Clarkson
• George Noyce – Jackie Earle Haley
• Based on – Shutter Island by Dennis Lehane
• Screenplay by – Laeta Kalogridis
• Directed by – Martin Scorsese 

Why is the movie called Shutter Island?

Book reference

The movie never clarifies this but the novel does—almost immediately. There’s a prologue then Chapter 1. Chapter 1 opens by talking about Teddy’s father being a fisherman and how when Teddy was a young boy they had gone out to the islands. 

So the island is actually named Shutter. 

Definition

As to the meaning of the word? You can see how Lehane uses slant dialogue to get around giving an actual definition, opting to leave it vague and somewhat menacing. It loads the place with a sense of unease. So we don’t get a clear answer in the story. But. Lehane, as a writer, chose the word for a reason. That means it’s worth diving into some of the etymology and definitions. 

According to Etymonline, shutter came about in the 1540s and meant “one who shuts”. The use to describe window-shutters came about in the 1720s. Lastly, the “photographic sense of ‘device for opening and closing the aperture of a lens’ is from 1862.” It’s a noun or verb. As in the thing that closes, like over a window or camera lens, or the act of closing. You could say, “After a bad year, Larry shuttered his business.” Or “After a bad year, the business shuttered.” Fun fact, most garage doors are roller shutters. 

In terms of Shutter Island, there’s the poetic connection between the name and the fact that Ashecliffe Hospital is somewhere people end up shut away from society. Once you’re there, you’re there. Closed away from the world. Stuck in this psychiatric facility. 

Anagram theory

Some fan theories have speculated that “shutter island” is an anagram for “truths and lies” or “truth/denials”. As Jack Pooley points out for WhatCulture, there are a lot of “anagram shenanigans” in the film. Edward Daniels = Andrew Laeddis. Rachel Solando = Dolores Chanal. That would be quite the coincidence. Of the words in the English language, Lehane chose shutter and island. They just happen to anagram perfectly to “truth and lies”. And he does that in a story where a character is lying to himself about the truth. And involves anagrams. Stranger things have happened. But there’s definitely reason to believe it was intentional. 

The themes and meaning of Shutter Island

Truth and lies: Teddy’s paranoia, guilt, self-loathing

Shutter Island is tricky because Teddy is our perspective character. He frames the events of the movie for the viewer. That use of the subjective is what makes Shutter Island so effective and seemingly tricky. We think we should believe him. We want to believe him. About Ashecliffe. About the psychiatrists. About the lighthouse. That he’s a US marshal on a mission. His fantasy deludes us. We’re not supposed to be smarter than him (at least not during the first viewing). Why?

By having us identify with Teddy and see through his POV, it gives us a window into the mania, paranoia, guilt, hallucinations, and self-loathing he’s experiencing. When we find out he’s actually Andrew Laeddis and why he’s at Ashecliffe, it’s brutal. We don’t want to believe it. Heck, some viewers still don’t believe it. The truth is sad and awful. His poor kids. His poor wife. Poor him. That sense of resistance and doubt all of us feel (or should feel) when Drs. Cawley and Sheehan reveal the truth to Andrew mirrors exactly what Andrew’s feeling. We know it’s probably true, but we don’t want it to be. So we look for excuses and reasons to believe the truth is false. 

This is powerful for multiple reasons. First, for anyone who hasn’t experienced significant trauma and grief, Shutter Island provides an opportunity for a vicarious experience, a way to safely journey through those emotions and, hopefully, gain even a brief conceptualization of what it must be like. Second, it’s a reminder to have some compassion for those who have experienced trauma. Their world is a complicated one. You have to imagine most of the people in Ashecliffe have some similar story to Andrew. If they were the main character of a film, maybe we’d sympathize with them. One Flew Over the Cuckoo’s Nest explored a similar theme. 

The idea of sympathy and empathy is funny because Teddy is so cruel to the patients. Early on, Cawley mentions how patients find some of the paintings calming. How does Teddy respond? “Screw their sense of calm.”

Later on, Cawley explains the divide between old and new school therapy. The old school prefers surgical intervention, specifically the lobotomy—put an ice pick in the brain, tear out some nerves in the frontal lobe, patients calm down—while the new school likes drugs, psychopharmacology. Same effect, different method. 

Teddy asks Cawley which Cawley prefers. The doctor says something along the lines of “Try and understand, you might just reach them.” In the background, a patient throws a tantrum and needs to be restrained. That prompts Teddy to say, “These patients, huh? It’s derisive and condescending. 

In summation, Teddy lacks any kind of empathy for the mentally ill. Because, someone deep inside himself, he knows he’s one of them. And that self-loathing is manifesting. 

This happens two other times. One, when interviewing a patient who cut off the face of a young woman. The second in Ward C. The first instance is petty. As the patient’s speaking, Teddy drags a pencil across paper. The sound is consistent and grating. It’s the kind of thing someone mentally healthy might be able to ignore, despite how annoying it is. But the patient isn’t mentally healthy so freaks out. Teddy enjoys causing this.

The second instance is violent. After the storm, power is out across the island. Teddy and Chuck sneak off to Ward C and encounter a dangerous patient on the loose. Separated from Chuck, Teddy gets jumped. The guy puts Teddy in a chokehold then takes the time to ramble and rave. There’s danger, but how much? The guy cares more about telling Teddy about the hydrogen bomb than he does hurting anyone. In response, Teddy beats the guy down then strangles him, only stopping because Chuck intervenes. Had Chuck not arrived in time…

We come to find out that Teddy had also assaulted George Noyce, who we see a few minutes later. It’s been weeks and Noyce still has bruises all over his face. Cut lip. Cut cheek. It’s brutal.

You don’t have to be Freud to pick up on the fact Teddy is projecting self-hatred. He’s a mentally unwell person who refuses to accept the reality of his own mental health so takes his self-loathing out on others. This means that everything he externalizes represents an internalization.

With all that in mind, think about Andrew and the choice he’s faced with. Die a man or live as a monster? He truly doesn’t believe he’ll get better. And also can’t stand what he’s become.  

What is a monster? The larger meaning of Shutter Island

When Andrew talks about being a monster, it’s not meant as a general label for the mentally ill. Rather, it’s the culmination of one of Shutter Island’s major themes. 

Think back over the movie. You may recall a lot of conversations about violence. Several times, characters wax philosophical about the ugliness and necessity of violence. Then we have an important juxtaposition between two events in Andrew’s life. Arriving at the liberation of Dachau, the concentration camp, and seeing the inhuman treatment of the Jewish people by the Nazis. And coming home to find his wife in the aftermath of drowning their children. 

In both cases, Andrew reacts with violence. Murderous violence. At Dachau, he and the other American soldiers lined up the Nazis who had surrendered. Then opened fire. At home, he has a moment of intense sadness with Dolores, who has clearly lost her mind, then shoots her in the stomach, after she asks him to “set me free”. 

Where is the line between good violence and bad violence? Does one even exist? Either way, once you’ve crossed into the world of the violent, can you ever find redemption?

This seems to be what Shutter Island means by its use of monster. That’s why you have Dr. Naehring with his quote about “Men like you are my speciality. Men of violence.” It’s why you have the Ward C guy ranting about atolls and h-bombs, the result of science wielded by the violent.  It’s why you have the strange scene with the warden as he drives Teddy. 

That scene can feel amazingly out of place. The warden isn’t a character who is developed. We see him once before and not again after. You could have just shown the car pick Teddy up and drop him off, cutting the conversation entirely. So why include it?

Because it’s thematically relevant. Teddy has, several times, rejected the idea he’s a violent person. He thinks of himself as decent. As an honorable marshal of the United States. but even he can’t continue to ignore the evidence to the contrary. There’s an anger in him. A rage. And even though he refuses the warden’s labeling, at the end, you see the switch flip. Teddy meets the final challenge of “would you be able to stop me before I blinded you” with an aura of intensity that pleases the warden. Teddy has, finally, stopped his denial. A foreshadow of what’s to come. 

Violence is what makes monsters. Not illness. The warden is as much a monster as Teddy. And that kind of gets at one of the scariest parts of Shutter Island: monsters are everywhere. Not just in mental hospitals, asylums, and wards. They can be in positions of power. They can be in government. And what happens when they have time, influence, and resources? This is why the Ward C patient says, “I don’t want to leave here, alright? I mean, why would anybody want to? We hear things here, about the outside world. About atolls. About H-bomb tests. Even though this guy is supposed to be “crazy”, he’s right. The “outside” world, the world you and I exist in, is as crazy as anything going on in Ashecliffe. Crazier, even. 

So Shutter Island isn’t just getting at the morality and psychologically of the clinically insane. It’s speculating on the sanity of civilization at large and showing that the divide between the “patient” and the “warden” is actually very thin. Whether that’s on the level of individuals or institutions or governments or world powers. 

The ending of Shutter Island explained

Recap

Shutter Island’s ending begins with Teddy’s journey to the lighthouse. In a state of supreme paranoia, convinced that Ashecliffe wants to turn him into a patient to keep him quiet, our hero arrives at the lighthouse, ready to do anything he must to save his partner Chuck and himself. There, Drs. Cawley and Sheehan confront Teddy with the truth—he’s actually Andrew Laeddis and in deep denial about the fact his wife, Dolores, committed filicide then begged Andrew to end her suffering. Filled with anger, guilt, and empathy—he did. Then went insane himself and fabricated the identity of Edward Daniels. 

We’re told that over the last 24 months, Andrew has been, as Teddy, incredibly violent. Often harming other patients, like George Noyce. There have been a few times that Andrew has resurfaced. Except he always reverts. This was a last, radical attempt to convince Andrew of the truth. Otherwise, the Board of Overseers has decided the hospital will conduct a lobotomy. 

In a moment that shows the subjective nature of the film, Andrew picks up a gun and fires. We hear the concussions. See red splash on the walls. Only for Dr. Cawley to be perfectly okay. The weapon is wood. Fake. It breaks in Andrew’s hands. 

A final hallucinatory conversation with Dolores leads Andrew to the truth. His real memories unlock. He passes out. 

When Andrew wakes up, he’s back to himself. In front of the doctors and the warden, he answers a series of questions that prove his mental health. “After she tried to kill herself the first time, Dolores told me she had an insect living inside her brain. She could feel it clicking across her skull, just pulling the wires just for fun. She told me that. She told me that, but I didn’t listen. I loved her so much, you know.” After a question. “Because I can’t take knowing that Dolores killed our children. And I…I killed them ‘cause I didn’t get her help. You know? I killed them.” 

Cawley states that Andrew has been on a tape. After every breakthrough, he goes back into the Teddy character and the delusions. Saying the same things as if on a script. The hope is that this time the tape has been erased.

In the final scene, Andrew and Sheehan talk on the steps of a building. Andrew, very pointedly recites his script as Teddy, mentioning needing to get off the island, and calling Sheehan “Chuck”. Sheehan signals to the doctors that the treatment didn’t work. 

Meaning

The twist ending relies on Cawley establishing that Andrew has been on a loop. That he goes through this whole performance as Teddy, wakes up as Andrew, then reverts to Teddy and says the exact same things. This idea of the loop sets up the final conversation. There, it initially seems like Andrew has already reverted. Except you can hear it in his voice—it’s performative. This isn’t the mental illness. It’s Andrew. Why would he pretend to be Teddy though?

That’s made clear when he goes off script to ask the question: Which would be worse? To live as a monster or die as a good man? 

Prior to that question, Dr. Sheehan had been crushed by Teddy’s reversion. But this moment of going off script, this self-awareness, surprises the doctor. He, of course, puts two and two together, which is why, as Andrew walks away, he says, “Teddy?” It’s not Teddy. It’s Andrew making a choice. Instead of being a monster kept in an asylum, he’s going to go out as a good man. 

There’s a tragedy to this because what if the treatment worked? Maybe Andrew is better now and could return to the world and start a new life. Instead of seeing if that’s the case, he would rather go out on his own terms. Because the idea of reverting back to someone else, someone he’s not, is too much to bear. In that way, it doesn’t matter if the treatment worked or not. Because even if it had, Andrew would still view himself as a monster. He’d still be unable to live with what happened. So he makes a choice that protects other people from his outburst but also, in his own way, puts his mind at ease. 

To make this even more definitive—the question wasn’t in the novel. It’s only in the movie. In the novel version of Shutter Island, the opposite happens. It’s pretty abundant that Andrew regressed. That he resumed thinking he was Teddy. No tricks. No moment of morality. The novel is a tragedy disguised as a psychological thriller. While the movie went with a little more of a silver lining. 

To be fair, Lehane did an interview with MTV in 2010 and said this: I would say that line, which comes across as a question, he asks it sort of rhetorically. Personally, I think he has a momentary flash. To me, that’s all it is. It’s just one moment of sanity mixed in the midst of all the other delusions. When he asks the question, he does it in such a way that, if he were to say it as a statement…then there’s no solution here but to stop the lobotomy. Because if he shows any sort of self-awareness, then it’s over, they wouldn’t want to lobotomize him. My feeling was no, he’s not so conscious he says “Oh, I’m going to decide to pretend to be Laeddis so they’ll finally give me a lobotomy.” That would just be far more s**cidal than I think this character is. I think that in one moment, for half a second sitting there on that island, he remembered who he was and then he asks that question and he quickly sort of lets it go. That was my feeling on that line.

While hearing from the author of the source material is important, it’s not the end all be all. This is Scorsese’s version, DiCaprio’s version. Given how they delivered that final scene, it seems like it was more than a momentary flash. But, either way, the result is the same. Andrew made a choice. 

There’s a larger, stranger question here. What is the effect of a lobotomy? NPR has an article about this. One section is called “What effect did the ice pick lobotomy have on patients?”

The answer: Freeman believed that cutting certain nerves in the brain could eliminate excess emotion and stabilize a personality. Indeed, many people who received the transorbital lobotomy seemed to lose their ability to feel intense emotions, appearing childlike and less prone to worry. But the results were variable, according to Dr. Elliot Valenstein, a neurologist who wrote a book about the history of lobotomies: “Some patients seemed to improve, some became ‘vegetables,’ some appeared unchanged and others died.” In Ken Kesey’s novel One Flew Over the Cuckoo’s Nest, McMurphy receives a transorbital lobotomy. 

As much as Shutter Island implies that Andrew won’t survive the lobotomy, it’s possible he did. More than that, it’s possible that he improved. As curious as that is to think about, this is a situation where the reality of what could happen can interfere with the poetic intention. Because the movie makes such a point that this is the end of Andrew, we should probably assume the lobotomy did not go well. That the result was vegetation or fatality. 

Why end on the lighthouse?

Over the course of Shutter Island, we were told the lighthouse was where all the bad stuff happened, including lobotomies. When Teddy finally broke in, he discovered it was mostly empty. Nothing shocking happened there. It was a normal, practical lighthouse. That means it’s unlikely the lobotomy takes place in the lighthouse. So why show it? 

Because it’s poetic. As we’ve associated that place with the act itself, by showing it as the final scene, after Andrew walked off with the staff for the lobotomy, the lighthouse serves as symbolism for the act itself. It’s confirmation without the actual, terrible visual of the pick up the nose and in the brain.  

There is, however, another deeper layer that no other explanation or analysis has ever discussed.

A lighthouse is supposed to serve as a beacon in darkness for those who are out at sea. It’s artificial light. False fire. 

Given how much Shutter Island focused on fire and water, there’s something deeply poetic in the image of a darkened lighthouse on the verge of the sea. That represents Andrew in the aftermath of the lobotomy. Empty. Darkened. Capable of light but not flame. It’s a fate in-between the extremes of water and fire—the two most important motifs in Shutter Island. 

Important motifs in Shutter Island

Water and fire and Rachel Solando

Rachel Solando is incredibly important to understanding Shutter Island. 

Initially, the film presents Rachel Solando as a patient who went missing, returns, then thinks Teddy is her husband. We eventually find out this was a nurse pretending as part of Cawley’s extreme treatment. Later, though, Teddy ends up in a seaside cave and finds the “real” Rachel Solando. 

It’s easy to chalk her up to a figment of Teddy’s poor, strained psyche. He’s already been having visions of Dolores and full on conversations with her in very cinematic fever dreams. We know he’s readily capable of hallucinations. The whole reason he discovers the cave is because he thinks he sees Chuck’s body on some rocks at the bottom of a cliff. 

The difference with Rachel is that all the previous hallucinations were momentary. They last less than a minute. Like the pistol is real. Then it’s fake. Dolores appears in places she couldn’t possibly be, like inside Noyce’s cell. Rachel, though, is there when Teddy enters the cave and there when he wakes up the next morning. Maybe she’s a figment. If so, it’s a figment way more subtle than Dolores standing unnoticed in the middle of a psych ward in a bright yellow sundress. 

It’s for one reason and one reason only that we see Rachel wake Teddy up—to make us believe she’s real. 

It’s the only thing in Shutter Island that’s up for debate. Especially when you go back through the movie a second or third time. You pick up a lot of little things that confirm Teddy’s a patient and everyone is in on Cawley’s performance. It’s why the Deputy Warden is so on edge around Teddy. It’s why none of the guards actually search for Rachel when Teddy’s out looking for her. It’s why the one patient waves at Teddy when he first steps on the grounds—they know each other. It’s why Naehring is such a jerk: he doesn’t believe Cawley’s treatment will work. It’s why multiple people look at Chuck when they mention Dr. Sheehan. 

Yet Rachel-in-the-cave is the one detail that isn’t telegraphed. It’s the only detail that’s seemingly left open for interpretation. 

Again, it’s easy to declare it a figment. Her name is an anagram of Dolores Chanal, Andrew’s wife. Just like Edward Daniels is an anagram of Andrew Laeddis. And it seems Andrew is at least somewhat aware of what he says and does as Teddy. Otherwise he wouldn’t be able to say the normal Teddy things to Sheehan at the end. You’d think if psychiatrist-on-the-run Rachel was real, we’d have some acknowledgement of it. Like Andrew admitting his illness but telling Cawley that Rachel didn’t feel part of it. But there’s nothing like that. Which means we can assume Andrew accepts Cawley’s declaration that Rachel was a hallucination.

That makes sense. He had been off his meds and not handling it particularly well. Especially after the Ward C confrontation, the Dolores hallucination, and Chuck’s body on the rocks. Seeing Rachel would, narratively, fall into the “rule of 3” (not to be mistaken with the movie’s rule of 4) that states things should happen in groups of three. Rachel would be the climax in this string of active imagingings. 

And because Teddy is alone and we’re isolated in his perspective, it’s easy to say Rachel’s presented more believably to the viewer because Teddy has no one to challenge his perception. It’s that subjective perspective impacting the way the viewer sees events. This is a Martin Scorsese movie, after all, so leaning into the nuance of cinematic language isn’t out of the question. 

With all that said, it would be fitting if Rachel were real. As it stops the movie from being solely one-dimensional. As in, if Rachel is a hallucination then Andrew is the problem and Ashecliffe is pretty innocent. Being one-dimensional is not a bad thing or an impossible thing. Not everything has to be Donnie Darko or Fight Club or Mulholland Drive. For the most part, Scorsese has been a straightforward filmmaker. His movies have twists and turns in terms of what happens and how (like The Departed), but they never leave you guessing. As opposed to Christopher Nolan with Memento or The Prestige or Inception. 

So there is an argument to be made that Rachel being real adds an important dimensionality to the story. And that her speech about “once you’re declared insane, then anything you do is called part of that insanity—reasonable protests are denial, valid fears [are] paranoia” supports this by showing that not everything an insane person believes and experiences is false. That there can be truth in madness. It just gets dismissed. That argument is reinforced by Cawley having a script for everything else Teddy says but being surprised about the woman in the cave. His response is, “Your delusions are more severe than I thought.” Not: “You always bring her up.” 

As much as that theory may appeal to some people, and as much as Rachel’s points about government experiments, MK Ultra, and the creation of “ghosts” fits the thematics of Shutter Island, it would be wild for her to actually be named Rachel Solando. That anyone would have a name that’s an exact anagram of Andrew’s wife? That’s hard to believe. Of course, that’s more believable if you buy into the theory that Edward was tricked and was never a patient. But you shouldn’t buy into that theory. 

So is there an answer about Rachel? 

Thankfully, yes. 

Water and fire and Rachel Solando part 2

You may notice that water is ever-present in Shutter Island. And that fire appears a lot, too. Remember, water and fire are poetically considered opposites. 

Given that the movie is based on a dichotomy between Teddy and Andrew, the water/fire dynamic should read as a purposeful contrast that’s part of the core tension between Teddy and Andrew. 

That connection is made pretty explicit. 

In Teddy’s (made up) memory, the tragedy occurred in fire. Someone burned down their apartment when Dolores was inside. In reality? The tragedy involved water. 

We even have that dream where Dolores is soaking wet but ash falls all around her and Teddy. Dolores even turns to ash. Then Andrew wakes up with water leaking on him. 

Fire is heavily present in most of Teddy’s dreams and versions of events. Meaning that we should associate fire, in any form, with fiction. And water with reality. When you keep these motifs in mind when re-watching, Shutter Island takes on a whole new layer of depth. The storm becomes symbolic. Chuck lighting Teddy’s cigarettes is symbolic (as Chuck is fueling the delusion). Teddy approaching Noyce’s cell in the near total darkness of Ward C and lightning match after match—that’s symbolic. Those matches going out is perfect, as Noyce is the first person to tell Teddy the truth rather than keeping up the performance. 

“But Teddy saw Chuck’s body on the rocks. It was swept away by the tide. That was a hallucination involving water.” 

Great point. But Chuck was a lie, right? He was just a character played by Sheehan. So the body on the rocks, swept away by the tide, only reinforces the symbolism of water representing truth, as we never actually see Chuck again. The next time the character appears is in the lighthouse, as Dr. Sheehan. 

With all that in mind, let’s return to the scene with Rachel. The two of them are in a cave. Huddled around…a fire.

Given what we know of the intentionality of the symbolism and motifs, we can’t ignore the fire and what that insinuates. Especially given the fact Teddy was just trying to find Chuck’s body, on the rocks, at the edge of the water. That he would seek refuge from the water by sitting next to the fire is the embodiment of the whole Andrew and Teddy dynamic. Whenever he gets too close to reality, he finds comfort in delusion. And this is the big one. The conspiracy that’s all-encompassing and goes right to the very top of the U.S. government. “Rachel” feeds into every fear and paranoia and delusion Teddy has. This is just another match he’s lit to keep the fiction going. 

Which is what makes that final shot of the lighthouse so powerful.

Questions and answers about Shutter Island

Who is George Noyce?

The short answer is that George Noyce was just another patient who Teddy happened to beat up. That’s it. 

The longer answer has to do with Andrew’s denial. Andrew was in such tremendous denial about what happened to his family that he created an entire personality to protect himself from ever thinking about it. That was Teddy. It seems Teddy reacted with extreme violence whenever someone challenged his delusion. We see moments of this at the end, in the lighthouse. That also explains the warden’s speech to Teddy about violence and why the guards and everyone else were so on edge. 

Noyce happened to call Teddy by his real name. That caused an attack. It seems Noyce is kept in Ward C specifically because of the tension between the two of them and Cawley doesn’t want to risk Noyce throwing a wrench into the illusion.

Did Andrew really liberate Dachau in World War II and take part in the reprisals?

It seems Andrew may have served in the military. But so much of what we learn about him as Teddy is fiction. It’s likely that the Dachau backstory and reprisals are nothing more than his way of fictionalizing what happened with Dolores and the kids and the way in which Andrew took her life in a mixture of mercy and payback.

That is the most straightforward interpretation. 

The more dramatic and poetic interpretation would be that yes, Dachau did happen, the reprisals happened, and that’s why Andrew responded how he did to Dolores. The combination of being part of that larger horrible thing and the more personal horrible thing is what caused him to break so badly.