Millard Fillmore actually said...
Now, therefore, I have issued this my proclamation, warning all persons who shall connect themselves with any such enterprise or expedition in violation of our laws and national obligations that they will thereby subject themselves to the heavy penalties denounced against such offenses and will forfeit their claim to the protection of this Government or any interference on their behalf, no matter to what extremities they may be reduced in consequence of their illegal conduct.
Context
Proclamation 57—Warning to United States Citizens Against Participating in an Unlawful Invasion of Cuba
04/24/1851