Parts of Czechoslovakia and Poland were parts of what had been Germany and populated by German-speaking people. Britain (and later the US) declared war on Germany, not the other way around; my understanding is that Germany at that time did not want war with Britain and had not expected the declaration.
Given Hitler’s views on the slavic peoples, Nazi Germany was always going to go to war with the USSR and Yugoslavia sooner or later, but I don’t find it implausible that Western Europe (and the US) could have stayed out of that war, had that been how we wanted to play it.
Technically Germany declared war on the US, not the other way around.
As for war with Britain (and France), they had formally committed to it in the event that Germany invaded Poland. In retrospect it was odd that Hitler seriously thought they might not attack him; it looks more like hope than rational expectation.
Parts of Czechoslovakia and Poland were parts of what had been Germany and populated by German-speaking people. Britain (and later the US) declared war on Germany, not the other way around; my understanding is that Germany at that time did not want war with Britain and had not expected the declaration.
Given Hitler’s views on the slavic peoples, Nazi Germany was always going to go to war with the USSR and Yugoslavia sooner or later, but I don’t find it implausible that Western Europe (and the US) could have stayed out of that war, had that been how we wanted to play it.
Technically Germany declared war on the US, not the other way around.
As for war with Britain (and France), they had formally committed to it in the event that Germany invaded Poland. In retrospect it was odd that Hitler seriously thought they might not attack him; it looks more like hope than rational expectation.
Human precommitment is pretty weak, and national precommitment more so (cf Budapest Memorandum elsewhere in the thread).