That’s not true, although I don’t blame you for not knowing about Executive Order 44. It’s not taught in public schools for understandable reasons, given how it reflects on the government.
Mormons also suffered a state sanctioned open season on their kind during which it was legally mandated that all Mormons within the state of Missouri be exterminated. They held fast to their faith, even to their deaths.
Presumably you and I agree this doesn’t prove Mormonism is true. It just proves sometimes people are tragically wrong about beliefs so important to them, they’re willing to die rather than give them up. Likewise with early Christians.