Around the world, Jews and non-Jews alike are reeling from the media coverage following the Hamas terrorist attacks in Israel on October 7. There can be very few who do not feel appalled by recent events and deeply concerned about the growing humanitarian crisis and potential escalation of violence. In this immensely painful and volatile situation, there are no easy routes forwards. Observers from afar may feel overwhelmed by a sense of powerlessness and incapacity to figure out what, if anything, they can possibly do.

In Western democracies there is faith in the rule of law and free speech; but even here, there are fierce debates over who should or should not be heard, and what constitutes inflammatory hate speech rather than a justifiable expression of opinion.

The situation was clearly different for bystanders — neither direct perpetrators nor immediate victims — under Nazi rule. Non-Jewish Germans who were shocked by Nazi antisemitism, whether in physical attacks, acts of humiliation, ever-tightening restrictions, or the torching of synagogues and smashing of homes and businesses in November 1938, could hardly complain to the authorities. It was, after all, the Nazi regime itself that instigated such violence. And the violence unleashed within the Third Reich and across Europe during the war was distinctively different from contemporary conflicts in the Middle East.

Even so, reactions today in some ways echo those of bystanders to the Holocaust. Are there more general lessons to be learned from the Nazi period?

In my new book I explore personal accounts by Jews and non-Jews in the Third Reich and beyond as Nazi terror evolved into genocide. Their life stories illuminate the responses of those I call the “muddled middle”, who might later be viewed as merely “bystanders”. Why did so many remain passive in face of horrendous violence against others? I highlight three factors that were variously important at the time, or in later self-representations: indifference, impotence and ignorance. Each is more complex than might appear.

First, there is the question of indifference. It is too simplistic to say that “Germans” hated “Jews”, or that there was something distinctive about antisemitism in Germany. Over the half century before Hitler came to power, German Jews were among the most assimilated in Europe. Class was generally more significant than religious heritage and there were high rates of conversion and intermarriage.

Antisemitism was far more vitriolic in eastern Europe where social and economic distress periodically gave rise to murderous pogroms. But the waves of impoverished Jewish immigrants, particularly after the First World War, did indeed contribute to rising antisemitism in Germany in some quarters.

Antisemitism was actively fostered by Nazi ideology and propaganda after Hitler came to power. Particularly among younger generations, subjected to Nazi education and youth organisations, and whose parents were often afraid to speak openly even in their own homes, it was hard to hear countervailing views.

But one did not have to be antisemitic to simply not care. Indifference could readily be fostered by segregation. From 1933, Jews began to be excluded from professions and social circles. It was “not done” to be seen consorting with Jews and it was bad for business to have Jewish managers or employees. The 1935 Nuremberg Laws further restricted relations between Jews, “half-Jews” and non-Jews. If there were few personal ties, there was little reason to care about the excluded.

Secondly, there is the question of impotence. The early brutal crackdown on political opposition rapidly made it clear that resistance was risky. By the mid-1930s, many former critics had become apathetic, even conformist. Repeatedly mouthing Nazi slogans and complying with regulations led racism to become second nature. Eventually, most accommodated themselves to life under Nazism. And in light of Gestapo and SS brutality, and the unlikelihood of wider support, critical spirits were unwilling even to express their opinions. Impotence was rooted in mutual distrust, apprehension and a realistic evaluation of the odds against being able to take effective action. After Kristallnacht, many non-Jewish Germans expressed shame and privately offered support and sympathy to individual victims, even as they continued to play their allotted roles in public.

By the late 1930s, a “bystander society” had developed in Nazi Germany, in which people remained passive in the face of violence against “others”. This was rooted not in individual psychological characteristics (although “character”, beliefs and values could make a difference), but rather in changing social relations and political circumstances.

There was a growing chasm between the included and the excluded; there were massive pressures for conformity; and widespread unease about visible intervention on behalf of victims. The preconditions for deportation and mass murder had been established.

During the war, the “Aryan” nation was mobilised in service of “Führer, Volk and Fatherland”. Many swallowed the Nazi myth of the defensive war against the supposed enemy of “Judeo-Bolshevism”. As mass killings began and terror turned into genocide, the challenges changed. The choices were now between becoming increasingly complicit, retreating into ineffectual silence, or engaging in resistance and rescue attempts, for which the penalties were ever higher. In this all-engulfing conflict, few could hope to come out unscathed. Identifications wavered, and individuals could shift from being a rescuer to being a perpetrator or beneficiary of murder and back again, according to circumstances. But no one could hope, in this maelstrom of escalating violence, to remain an “innocent bystander”.

Finally, there is the question of ignorance. Ignorance can be achieved by actively ignoring — choosing to look away, to turn a blind eye. Many non-Jews had practised this from the start, dropping friendships with Jews, excluding them from social circles, not inquiring after they had “lost contact”. Ignorance was furthered by official policies of spatial as well as social segregation. Deportations, deception, and disguise of distant killing sites were not merely perpetrator subterfuges to gain compliance among victims, but also allowed bystanders to continue turning a blind eye. And ignorance was also a form of denial. “We never knew anything about it” became something of a national refrain when citizens were forced by the Allies to confront atrocities committed in their name. But not merely had many people actually “known”, they had also done far more than they would willingly own up to.

Exact figures are hard to calculate, but in addition to the notorious death squads or Einsatzgruppen, the SS units, and members of police battalions, perhaps as many as three-quarters of a million soldiers were involved in perpetrating or facilitating the “Holocaust by bullets” on the eastern front, and they sent letters and photographs home. By the time the gassing experts who had honed their skills in the “euthanasia” killings of the mentally and physically disabled were operating the extermination camps in Poland, and by the time Auschwitz came into full swing, there was already significant participation in and widespread knowledge of mass murder.

Furthermore, hundreds of thousands were involved in the exploitation of forced labourers, the “germanisation” of regions in annexed and occupied territories, and the ghettoisation of Jews that eventually facilitated extermination. And millions more benefitted from the “Aryanisation” of Jewish properties, and acquired the goods and clothing of murdered Jews at knock-down prices.

The precise details of the gas chambers may have remained unclear but the removal of Jews not merely from their homes but also their place on this Earth was all too evident. Ignorance in the self-exculpatory sense — if I did not know, I could not have done anything — was nothing more than a postwar defence.

Of course this summary is necessarily schematic and individual stories reveal the complexities involved in life under Nazi rule. Particularly where emotional, political, cultural or moral ties still crossed the newly imposed racial divides, individual Gentiles refused to abandon a sense of common humanity with outcasts of Jewish descent. Some prioritised personal relationships and clung to loved ones, some took the risks involved in trying to rescue even those they did not know personally, some retreated into silence with occasional gestures of support. The experiences of those who could not remain “merely bystanders” may help us understand the circumstances that turned the unthinkable into reality.

Bystander Society: Conformity and Complicity in Nazi Germany and the Holocaust by Mary Fullbrook is published by OUP on November 1