On thlis Date, April 18, in Hisotry:
1775 Paul Revere & William Dawes warn "the British are coming!" - also, according to Sarah Palan, warned the British that the British were coming.
I say that jokingly, but there is some truth in it. On Revere and Dawes' ride to warn locals that the British were coming a little outpost of British troops caught them, held them, and thought they were insane for making such warnings they knew nothing about and let them go.