Rockets, flying through the air for the purpose of carrying mail—not bombs.

If Postmaster General Arthur E. Summerfield’s 1959 remarks had come true, that would have been the future. “Before man reaches the moon, mail will be delivered within hours from New York to Califonia, to Britain, to India or Australia by guided missiles,” he predicted, according to Engineering 360. Alas, “missile mail” quickly proved to be as unfeasible as that name made it sound.

On this day in 1959, USPS delivery of mail by rocket took place for the first and last time. The USS Barbero, a submarine, fired an unarmed cruise missile carrying about 3,000 pieces of mail where its payload would normally be. Summerfield was on hand to help place the two red and blue mail containers in the rocket.

“The missile was fired toward the Naval Auxiliary Air State in Mayport around noon,” writes Engineering 360. “It reached its destination 22 minutes later. The mail was then sorted and routed as usual.”

For the occasion, the Post Office Department (today known as the United States Postal Service) had set up an office on the submarine. The mail it handled was validated with a USS Barbero postal mark over the stamp.

There was something else different about this mail, writes Nancy A. Pope for the National Postal Museum: all 3,000 pieces were copies of the same letter, written by the Postmaster General.

The letter went out to U.S. leaders including President Eisenhower as well as postmasters from around the world, she wrote. The crew of the submarine also each got a copy of the letter and envelope, which Summerfield described as “a significant philatelic souvenir.”

“The great progress being made in guided missilry will be utilized in every practical way in the delivery of the United States mail,” he wrote. “You can be certain that the Post Office Department will continue to cooperate with the Defense Department to achieve this objective.”

But it was not to be. The missile which carried the mail was a Regulus I, “the first operational U.S. Navy cruise missile,” according to the National Air and Space Museum. And the whimsical test had another motivation behind it, writes Pope in a separate piece. “Unlike secret tests, a mail-carrying missile test would publically display the accuracy and reliability of U.S. missiles,” she writes.

This was only two years after the U.S. flew a B-52 around the world without stopping to refuel in order to prove another point about military capabilities, after all. The Cold War arms race was in full swing–and a demonstration of that level of precision with a rocket was meant to be threatening.

It was a successful test (unlike an explosive experiment by a teenager in Texas), but there were no more experiments with using missiles to deliver the post. The Navy had proved its point about the speed and accuracy of the Regulus I. Serious consideration of flying mail delivery would have to wait for drones.