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In page Gaul:

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As many as one million people (probably 1 in 12 of the Gauls)[citation needed] died, another one million were enslaved,[6] 300 clans were subjugated and 800 cities were destroyed during the Gallic Wars.[7] The entire population of the city of Avaricum (Bourges) (40,000 in all) were slaughtered.[8] Before Caesar's campaign against the Helvetii (Switzerland), the Helvetians had numbered 263,000, but afterwards only 100,000 remained, most of whom Caesar took as slaves.[9]