Niko can say only so much in his letters, but I recognize an incipient pacifist, appalled by the destruction of the war. His mother surely heard echoes of Kurt’s dispatches from the front during World War I. “It’s so unspeakably sad that so much beauty is being destroyed, all that was once dear and familiar to me from previous travels,” Niko wrote. “Who knows if I will ever see these places again? Also Elba, Saint-Tropez, Florence­—­everything is part of the war now and gone.”

  Nor was he still at large in a land of unlimited caloric extraction. “Please send food, like bacon,” he wrote on September 12, 1944. “Most of the time I’m hungry.” The day before, American forces had taken their first steps on German soil, across the River Our from Luxembourg.

  On September 24 Niko began five weeks of training to become a sergeant. But the course was called off two weeks in, and he was sent with his regiment to a succession of postings—first in Dux (now Duchov in the Czech Republic), then coastal Holland, then back to Dux, and to Holland again, and finally, in early December, to what would be his last theater of the war. “A brief greeting en route,” he wrote his mother from near the Rhineland town of Münster. “Who knows where we’re going.”

  His destination became clear within days, when the Nazis went into what would turn out to be their death spasm. In German the offensive was known as Wacht am Rhein, or Watch on the Rhine, although histories of the victors call it the Battle of the Bulge, after what the Germans’ initial incursion looked like on a map. Niko’s unit was deployed to the Eifel, the wild hills of Germany’s western borderlands. There, somewhere between the German town of Geichlingen and Vianden, in Luxembourg, he hunkered down in an antiaircraft emplacement, on a ridge exposed to the pounding of American artillery.

  On Christmas Day he scratched out a letter home. “It’s so dreadfully difficult for all of us, but we must stick with it and endure,” he wrote. “I’m lying in a dugout, barely covered by a tarp. It’s freezing cold outside and a feeble sun relieves the long moonlit nights. It’s dark now, which means no attacks from above. The artillery barrages provide the only Christmas music. When it stops, it feels eerie. I hadn’t counted on being in the midst of this again this year. But if God wills it, I’ll get out of here in one piece.”

  Niko may not have realized the extent, but the western Allies were steadily recapturing territory lost to the initial Nazi advance. Exploiting beachheads from the Normandy invasion, they had massed almost eight times as many men in France and Belgium as the Germans, and held an even greater advantage given how much matériel and manpower Hitler now had to send east to fend off the Soviets. Meanwhile, each winter-clear day reminded Niko that the Luftwaffe had been bombed and strafed into irrelevance. “All day long fighter planes circle about, sweep down on us, over our heads, like vultures after their prey,” he wrote. “Beginning at dawn we lay in wait at our cannons to defend ourselves when they get too close. In between we take on the role of regular artillery and shoot across the front line. Thus the days go by . . .”

  Over the following weeks he and another soldier dug themselves a better position. They lined it with fir branches and fit it with a small stove, only to discover an infestation of lice, 135 of which he harvested from his sweater one day. “It’s so terribly difficult just now, and sometimes hopeless,” he wrote on January 26. Then he seemed to refer to his inner boundlessness: “It’s easy to lose faith that one might get out of here alive. But I’m amazed over and over again by my protective, lucky star, considering the horror around me.”

  By January 29 his unit had abandoned its ridgetop position and retreated to a nearby village to await further orders. “What lies ahead I don’t know, but I believe it’s going to be rougher yet,” Niko wrote.

  We’ve had several dark days already. Being in this village is a bit more quiet. But heavy artillery lands here every so often. When I started this letter a direct hit struck the house next door. And having been spared, there’s this feeling of gratitude that envelops you, displacing the gripping fear just passed. You know, when life gets to be so primitive—(another shell exploded just now)—and we’re constantly seeking shelter, like homeless people, shelters that often seem bizarre, that’s when a simple room with a warm stove, and a bit of straw to rest, makes you as happy and content as a small child.

  My father’s unit seems to have stayed in this village for another week or two, when he realized he was only a short hike from Grünhaus bei Trier, home to the winery of the von Schubert family, whose son Andreas had been a classmate at boarding school. Niko and another soldier walked the few kilometers from their encampment, and Frau von Schubert fed them a meal and shared news of her son, then off serving with a tank division. German officers had commandeered the property and were “lolling around amidst the antique heirlooms of the family,” Niko reported in what would be his last letter home. “The fate of this lovely castle will be sealed soon too, as the Americans aren’t far off. Now and then an artillery shell comes crashing in.”

  A short hike from Trier, this direct descendant of that city’s chief rabbi, wearing the swastika of the Wehrmacht, finished his finest meal in months and resumed his retreat.

  Over the next few weeks, Niko and his unit struggled to outrun the American advance. They had long since abandoned their 88mm guns to more easily lose themselves in the woods. Formal units dissolved and small bands of soldiers carried on in random fashion. Niko spent one night on an island in the Rhine. On March 29, after crossing a field to reach the square of the village of Wehen, just outside Wiesbaden, he was taken prisoner by Americans in jeeps.

  But before that, my father was witness to an episode he never spoke to me about. I learned of it only after his death, and then only because he had shared it with my brother-in-law, whose insistent way in conversation had a way of breaking down obstructions in the Human Flowchart.

  By early 1945, as it became clear that they faced a choice between “an end with horror and horror without end,” more and more Germans resigned themselves to the first. Nonetheless, in mid-February, Martin Bormann, Hitler’s private secretary, issued a directive ordering “summary courts martial”—rough justice to cull the Wehrmacht of defeatists. “Anyone not prepared to fight for his people but who stabs them in the back in their gravest hour does not deserve to live and must fall to the executioner,” the order read.

  Sometime during those bleak days before capture, my father and a half dozen or so others in his unit concluded that the fight was lost. But as they mulled over how best to turn themselves in, the ranking soldier among them, a true believer, began to draw up plans for guerrilla warfare. Their differences led to an angry argument.

  It became clear that this ranking officer was committed to a fight to the death. “What we’re going to do,” this officer began, turning his back—whereupon one of my father’s fellow soldiers raised a pistol and shot him dead.

  In early April the Americans transported Niko west to France, to a camp on the outskirts of Le Mans, a tent city where sixty thousand prisoners slept under shared blankets on bare ground. They were fed bread and ersatz coffee for breakfast, a pint of tomato or green-bean soup for lunch, and two ounces of cheese or canned pork for dinner. The Allies would eventually take into captivity some five million POWs, a total that overwhelmed them. But rations amounting to 850 calories a day, barely a third of what the average male adult needs to maintain his weight, were intentionally punitive. And although this was an American camp, many of the guards were French and, my father recalled, particularly hostile. The Geneva Convention mandated that signatories feed and care for POWs at the same standard as their own troops, but a trick of nomenclature got the Americans off the hook by defining captives like Niko not as POWs but as DEFs—disarmed enemy forces. My father once told me the fate of a fellow German prisoner caught stealing chocolate. He enjoyed nothing but chocolate every day until he died.

  Niko would always be grateful to one of the first soldiers to process him, a GI from Chicago, who confiscated his Leica but insisted on compensating him with several cartons of cigarettes—a cache my father would dip into over the coming weeks to barter for food. He soon caught another break, in the unlikely form of an ear infection and a temperature of 104 degrees Fahrenheit. This won him transfer to a US Army hospital, where he was given morphine for the pain and had the ear drained. During his convalescence he slept in a bed with sheets and pillows and ate meals on trays. After Germany’s surrender, he was shuttled from camp to camp, eastward through France, until finally, in midsummer, he joined hundreds of other POWs on a train, in open cattle cars where prisoners could only stand or squat.

  From the terror of aerial bombardment to widespread hunger, the Allies visited on the Germans a succession of turnabouts during the final months of the war and its aftermath. Here it was the dehumanization of transport by cattle car. Over three days, Niko and his fellow POWs made halting progress or found themselves shunted onto sidings to await a new locomotive. Confined to the cars at all times, they were left exposed to the elements, as well as to the waste and stench that rose around them and, as they discovered one day while left on a siding in Strasbourg, something potentially worse.

  A transport filled with drunken French soldiers had pulled alongside the prisoners’ train. When the Frenchmen recognized this adjacent gallery of Germans, several raised their rifles and began to fire, below, above, and for all the prisoners knew, right at them. The American guards were almost as panicked as their captives. The GIs couldn’t speak French, didn’t have time to procure an engine, certainly couldn’t let their prisoners go. A reprieve came only when the train carrying the French soldiers pulled out of the station. “Another of my nine lives,” Niko called it.

  On August 13, Kurt wrote in English to Maria in Freiburg: “What weighs on our hearts is of course Niko’s fate. Elisabeth has heard no news from him since February, when he was in the east. There is very little chance of getting news from him for an indefinite time to come, and it will not even be possible to find out in the near future whether or not he is alive.”

  A few days after Kurt wrote that letter, Niko was routed through a US processing center in Heilbronn. He was given clean clothes, a small sum of money, and discharge papers. It took more than three months after Germany’s surrender, but he was now officially free to go home.

  On the morning of August 17 he arrived at Munich’s main station and hopped a tram for Nymphenburg, where my grandmother still lived in an intact home on the Südliche Schlossrondell, one of two gently curving roads that lead to the palace. In her pocket calendar Elisabeth made a note of his arrival. 10 Uhr: Niko kommt—sehr erschöpft, 121 Pfund! (10 a.m.: Niko arrives—extremely exhausted, 133 pounds!)

  The next day: Niko ausschlafen, hat Dysenterie. (Niko sleeps in, has dysentery.)

  He survived the war with no apparent psychological malady, and no physical ones other than that dysentery, the ear infection, and a permanently discolored toenail from having dropped a 450-pound V-8 engine on his right foot.

  And yet, a detail my father shared about his return to Munich, on a morning he recalled as sunny and warm, sticks with me. When he reached his mother’s house, he didn’t simply walk through the door. First, he rang the bell.

  Another day, another revelation to wrestle with.

  The bookstore is tucked away off Friedrichstrasse in central Berlin; the book, a 2015 account called Blitzed: Drugs in Nazi Germany, is a chronicle of depravity and delusion. Historians differ over the soundness of some of author Norman Ohler’s arguments. But he makes the case that a methamphetamine called Pervitin put the blitz in the Blitzkrieg, allowing the Wehrmacht to go without sleep over three days in June 1940 and breach the borders of France and Belgium before either country could mount a defense. Later, desperate to penetrate the Thames estuary during the waning months of the war, the Germans built torpedo-bearing mini-submarines and doled out cocaine-infused chewing gum to poorly trained teenage pilots, many of whom wound up drowning after prolonged sleep deprivation. And most pertinently to me, Blitzed contends that in July 1943, Dr. Theodor Morell, the beefy Hessian who served as the Führer’s personal physician, began to dope up the man he referred to in his notes as “Patient A.” Morell kept Hitler under the influence for most of the rest of the war. If he hadn’t fortified him by doing so, the doctor claimed, “Germany would have been brought to its knees.”

  The family of my grandmother Elisabeth Merck founded and still runs the world’s oldest drug and chemical company. Among the substances Hitler apparently took, Merck produced two. One was the cocaine for which the firm was world-renowned. The other, an opioid called Eukodal, had a particularly insidious effect. Beginning in late 1942, Morell seems to have administered more than a thousand doses of Eukodal to Hitler over an eight-hundred-day span. This regimen, the book contends, turned the Führer into a junkie. After US Air Force B-17s destroyed the Merck factory in Darmstadt in December 1944, Hitler’s doctor could no longer procure Eukodal and Patient A went cold turkey.

  All of this leaves me swimming in a cloud of implications.

  In 1826, my great-great-great-grandfather Emanuel Merck isolated the active ingredient in poppy seeds in his Darmstadt pharmacy and began to mass-produce alkaloids of standardized quality. Merck soon became famous for the purity of its morphine, and by the 1880s the firm enjoyed a virtual monopoly on the world’s legitimate cocaine trade. By the early twentieth century Merck flake had such a reputation that counterfeiters in China would slap phony labels on vials to make them look like the real “Red Capsule” thing, pictured in this advertisement.

  Pharmaceuticals stood out as one of Germany’s few thriving industries during the economic uncertainty between the wars. One reason was Eukodal, essentially the same opioid as OxyContin, that scourge of rural America today. Merck had introduced the drug in 1917, marketing it as a painkiller and cough suppressant, but Eukodal caught on through the hedonistic twenties for its euphoric qualities. Twice as effective at relieving pain as morphine, capable of delivering a loftier high than heroin, Eukodal was a favorite recommendation of doctors, some of whom became regular users themselves. The drug wasn’t so much a cousin to morphine as a sibling—“Little Sister Euka,” in the words of one of its devotees, Thomas Mann’s son Klaus. Or as a connoisseur of later vintage, William S. Burroughs, put it in Naked Lunch: “Like a combination of junk and C [heroin and cocaine]. Trust the Germans to concoct some truly awful shit.”

  Morrell began to treat Hitler with Eukodal in July 1943, on the eve of a high-stakes meeting with Mussolini. The Allies had just landed in Sicily, and the Führer was desperate to keep Italy in the Axis camp. Under the influence, Hitler performed: he filibustered for almost three hours, until Il Duce reconfirmed Italy’s solidarity with Germany even as Allied bombers were pummeling Rome. By October, Ohler reports, Hitler was receiving up to four times the typical therapeutic dose.

  Merck drugs figured again in July 1944, in the aftermath of the failed Valkyrie plot to kill Hitler. The explosion of a bomb in a briefcase, planted by the officer Claus von Stauffenberg beneath a table at the Wolf’s Lair in East Prussia, left Hitler with a perforated and bleeding eardrum. Another doctor was summoned—an ear, nose, and throat specialist named Erwin Giesing. Officially, the Nazis regarded cocaine as a degenerate sacrament of Weimar values. But Giesing prescribed Merck’s finest in a 10 percent topical solution, and Hitler was pleased with its effect.

  Norman Ohler describes the onset of overconfidence and megalomania over the next few months as the Führer, even as losses mounted in the east, proposed a counteroffensive in the west. Giesing swabbed cocaine on Hitler’s nose and throat each morning, Ohler writes, while Morell continued to administer Eukodal, now at twice the dosage of a year earlier. The result was “the classic speedball—the sedating effect of the opioid balancing the stimulating effect of the cocaine.”

  By the time of the December 1944 raid that destroyed the Merck factory, Hitler, in the picture Ohler paints, has become distracted and sleep-deprived, with needle marks tracking up and down jaundiced, tremulous arms.

  In fact, Hitler’s bunker mentality had discovered in Eukodal the ideal end-time drug for the hapless final battle. His numbness, his rigid view of the world, his tendency towards the fantastical and the unscrupulous transgression of all boundaries­—­all of this was ominously supported by the opioid that he used so frequently in the last quarter of 1944. During this time, when the Allies were entering the Reich from both east and west, the powerful narcotic erased any doubts about victory, and made Hitler even more unfeeling about both himself and the outside world.

  By January, Morell could no longer administer Eukodal because Merck could no longer produce it. Two months later Hitler issued his so-called Nero Decree, the order that every last shred of German infrastructure—highways, railroad tracks, bridges, power plants, factories, banks—be destroyed.

  I had hoped to discover that Merck pharmaceuticals got Hitler hooked, clouding his judgment so that, as the Wehrmacht suffered reversal after reversal and German cities were destroyed from the air, withdrawal helped send him into a spiral that hastened the end of the war. Instead, Blitzed makes the case that cocaine and Eukodal propped him up and amped him up. The high from the drugs, then the crash from Eukodal’s sudden unavailability, inured him to reality and encouraged his basest instincts. Merck alkaloids ensured that the Nazi war machine would remain deployed at full force, where a sober leader might have folded his hand.