Aaron, what an interesting question.
Here are links to
Poetry magazine from October and November 1939. There are some poems there that clearly address the outbreak of war or its threat.
https://www.poetryfoundation.org/poe...2/october-1939
https://www.poetryfoundation.org/poe.../november-1939
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I have a sense that the upcoming horror of the war was best foreseen by those poets who knew firsthand about the civil war in Spain. That's something I hope to look into.