Jack chose Roger and Maurice to accompany him during his raid on the shelters when he told the rest of his tribe that he would 'get fire from the others' He actually stole the means to make fire, namely Piggy's glasses.
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In chapter 10: the Shell and the Glasses Jack informs his tribe, and I quote, "But tomorrow we'll hunt and when we've got meat we'll have a feast---" Bill then puts up his hand and asks, "What'll we use for lighting the fire?" Jack blushed but then informed his tribe that, "We'll take fire from the others." Eventually Jack did set out, with Roger and Maurice, to raid Ralph's camp, not for fire but for the means by which fire could be made, namely Piggy's glasses.