In the late 1950s, the United States Postmaster General was looking for ways to deliver mail faster over greater distances. Drawing inspiration from Cold War technology, he decided to use the most powerful delivery device available: a Regulus cruise missile. In June, 1959, the nuclear warhead was removed from one of the rockets and replaced with a shipment of 3,000 commemorative postcards. Then, instead of just firing the missile from one post office to another, it was loaded onto a submarine and carried out into the Atlantic Ocean off the coast of Florida, and launched at a speed of Mach 2 (680 miles/second) toward a special landing site outside Jacksonville. From there, the mail had to be retrieved and sorted before finally being delivered. In spite of the enormous expense and the impracticality of this procedure, the Postmaster General declared the experiment a great success. Albeit one that was destined to never be repeated.