Latest best theory on the U.S.S. Maine is a slow burning coal fire in the forward coal bunker. After slowly burning for hours undetected (an all-too-common problem of the era) the heat alone set off the powder bags in an adjacent magazine. Hearst did the rest.
France did indeed launch an assault on Germany as a way to belatedly "intervene" on behalf of Poland, but the event came to nothing. To argue that this was the trigger for the second world war, however, flies in the face of a good volume of historical documentation.
Seamus
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