You Fools!: Government Convinced Martians Were Going To Make Contact In 1924
In 1924, during Mars's opposition (when Earth, on its inner orbit, passes between the Sun and Mars) the US Navy sent a telegram alerting all its stations to be on the lookout for possible alien contact from the red planet. WOW!
Turns out that during the 1924 Mars opposition--when Mars would be closer to Earth than it had been since 1804--the secretary of the Navy sent a telegram to all naval stations asking them to "COOPERATE ASTRONOMERS WHO BELIEVE POSSIBLE THAT MARS MAY ATTEMPT COMMUNICATION BY RADIO WAVES WITH THIS PLANET WHILE THEY ARE NEAR TOGETHER."
BWAHAHAHAHA -- Martians! Like, aliens from Mars! BWAHAHAHAHAHA! I've got news for you: there aren't any aliens on Mars. Pluto, yes, but they're so pissed off we reclassified their home as a dwarf planet they don't have anything to say to us.
UPDATE: I lied, turns out they do have something to say: "F*** you -- have fun with the global warming".
Navy was ordered to listen for Martians in 1924 [scifiwire]
Thanks to junkyard dog, who eats scrap metal and tires and shit because that's what junkyard dogs do.