Almost a dozen years before Rosa Parks famously refused her seat to a white man, Jackie did the same thing on an Army bus. This didn't result in any sort of moment for the civil rights movement to coalesce around; instead it led to Jackie being court martialed and prevented him from fighting overseas (which is kind of a silver lining). Instead, Jackie spent the rest of his army days coaching athletics, where he met a former Negro Leaguer who encouraged him to resurrect his baseball career.