Concerning the hypothetical response to Nazi Germany provided no invasion of other countries had occurred

First, let’s be clear: this is speculative reasoning based on real historical patterns, not a definitive prediction.
The Holocaust and related atrocities were among the darkest chapters in human history, and discussing them requires sensitivity. I’ll break this down step by step, drawing on what we know from the actual 1930s and early 1940s, to hypothesize how the international community might have responded if Nazi Germany had remained largely isolationist in terms of territorial expansion (beyond, say, the Anschluss with Austria in 1938, which was bloodless and somewhat tolerated at the time).

1. Historical Context: What Actually Happened Pre-Invasion

To set the stage, even in our real timeline, the Nazi regime began its campaign of ethnic cleansing, persecution, and eventual genocide well before major invasions like Poland in 1939. Key events inside Germany (and later occupied territories) included:

• The Nuremberg Laws (1935), which stripped Jews of citizenship and rights.
• Kristallnacht (1938), a nationwide pogrom that destroyed Jewish businesses and synagogues, resulting in hundreds of deaths and thousands of arrests.
• The early stages of the Holocaust, including forced emigration, ghettoization, and euthanasia programs (e.g., Aktion T4 targeting the disabled), which were underway by 1939.

Despite widespread knowledge of these atrocities—reported in international media and by diplomats—the global response was muted. Why? Several factors:

• Isolationism and Appeasement: The U.S. was deep in the Great Depression and adhered to isolationist policies (e.g., Neutrality Acts). Britain and France pursued appeasement, as seen in the Munich Agreement (1938), hoping to avoid another world war after the horrors of WWI.
• League of Nations’ Weakness: The League was toothless without U.S. membership and failed to enforce sanctions effectively (e.g., it condemned Italy’s invasion of Ethiopia but did little).
• Antisemitism and Indifference: Antisemitism wasn’t unique to Germany; many countries (including the U.S. and Britain) had restrictive immigration policies. The Evian Conference (1938) saw 32 nations discuss Jewish refugees but resulted in almost no action—most delegates expressed sympathy but refused to accept more immigrants.
• Economic Ties: Germany was a major trading partner for many nations. Boycotts were discussed but rarely implemented robustly.

In short, before WWII escalated with invasions, the world largely watched from afar, issuing condemnations but avoiding direct intervention.

2. Hypothetical Scenario: No Major Invasions

Now, let’s tweak the timeline as you described: Nazi Germany annexes Austria (which happened with minimal international backlash) but stops there—no Czechoslovakia, no Poland, no Low Countries, no France, no Soviet Union. The regime focuses inward on “Aryanization,” ethnic cleansing, and genocide within its borders (targeting Jews, Roma, LGBTQ+ people, political dissidents, the disabled, etc.). Would the international community allow this? Would they intervene?

Likelihood of Tolerance (or “Allowing” It)

Unfortunately, based on historical precedents, it’s plausible that the world would have turned a blind eye or responded inadequately, at least for a significant period. Here’s why:

• No Direct Threat to Other Nations: Without invasions, there’s no immediate casus belli (justification for war). In real history, the Holocaust intensified during the war, but pre-war persecutions didn’t provoke military action. Countries might have viewed internal German affairs as sovereign matters, much like how the world ignored Stalin’s purges in the 1930s (which killed millions) because they were “internal.”
• Diplomatic and Economic Responses, But Weak Ones: There could have been sanctions, trade embargoes, or diplomatic isolation, similar to the ineffective boycotts against Nazi Germany in the 1930s. The U.S. might have recalled its ambassador (as it did after Kristallnacht), and there could be more conferences like Evian. But enforcement would be spotty—Germany could trade with sympathetic regimes (e.g., fascist Italy, Japan, or neutral states) or even the Soviet Union via something like the Molotov-Ribbentrop Pact.
• Public Opinion vs. Government Inaction: Media coverage might stir outrage (e.g., reports from journalists like William Shirer), leading to protests or private aid efforts (like the Kindertransport, which saved ~10,000 Jewish children). But governments were risk-averse; without a broader war, leaders like Chamberlain or Roosevelt might prioritize domestic recovery over humanitarian intervention.
• Comparisons to Other Genocides: History is full of examples where the international community failed to act decisively on internal atrocities:
  • The Armenian Genocide (1915–1923) by the Ottoman Empire: Widely known but not stopped; no major intervention.
  • The Holodomor in Ukraine (1932–1933): Stalin’s engineered famine killed millions; the world knew but did nothing substantive.
  • Later examples like Rwanda (1994) or Bosnia (1990s) show that even with UN involvement, intervention often comes too late or not at all without strategic interests at stake.

In this scenario, without the catalyst of WWII, the Holocaust might have unfolded more slowly or differently (e.g., more emphasis on expulsion than extermination camps), but the pattern suggests limited external pressure.

Likelihood of Intervention

Direct intervention seems unlikely, but not impossible under certain conditions:

• Military Intervention? Probably Not: Invading Germany to stop internal genocide would have been unprecedented and politically suicidal in the 1930s mindset. No major power had the will or mandate for “humanitarian intervention” as we think of it today (e.g., post-WWII UN frameworks). The U.S. public was overwhelmingly isolationist until Pearl Harbor in 1941.
• What Could Trigger Action?
  • Refugee Crises: If mass expulsions created border chaos (e.g., Jews fleeing to neighboring countries), it might force responses, like temporary camps or forced repatriation (as happened with some refugees in real history).
  • Espionage and Intelligence: If Allied intelligence uncovered systematic genocide (as they did in WWII via reports from Polish resistance), it might galvanize action—but without war, intelligence sharing would be limited.
  • Shifting Alliances: If Germany allied with other aggressors (e.g., Japan invading Asia), it could draw in powers like Britain or the U.S. indirectly. Or if internal instability led to German aggression spilling over (e.g., targeting ethnic Germans in Poland without full invasion), it might escalate.
  • Long-Term Pressure: Over years, sustained boycotts or cultural isolation (e.g., Olympic boycotts, as debated for the 1936 Berlin Games) could weaken the regime economically, potentially leading to internal collapse or reform. But this isn’t “intervention” per se.

That said, a wildcard: If figures like Winston Churchill (who was anti-appeasement) gained power earlier in Britain, or if FDR pushed harder against U.S. isolationism, there might have been stronger diplomatic efforts or even covert support for anti-Nazi resistance inside Germany.

3. Broader Implications and Ethical Reflections

In this alternate history, the absence of WWII might mean fewer total deaths globally (no Eastern Front, no Pacific War), but it could prolong the suffering inside Germany. It raises uncomfortable questions about human rights: When does “internal affairs” cross into universal moral imperatives? Post-WWII, institutions like the UN and the Genocide Convention (1948) were created partly in response to the Holocaust, suggesting that such a scenario might have accelerated global norms against genocide—but only after the fact.

Ultimately, history suggests the international community would have de facto allowed it through inaction, much as it did pre-1939. Intervention would require a paradigm shift that didn’t exist then. It’s a grim reminder that geopolitical interests often trump humanitarian ones, though we’d like to think we’ve learned since.