What was the original motivation for developing the Internet?

From the launch of Sputnik and the U.S.S.R. testing its first intercontinental ballistic missile, the Advanced Research Projects Agency (ARPA) was born. ARPA was the U.S. government's research agency for all space and strategic missile research. In 1958, NASA was formed, and the activities of ARPA moved away from aeronautics and focused mainly on computer science and information processing. One of ARPA's goals was to connect mainframe computers at different universities around the country so that they would be able to communicate using a common language and a common protocol. Thus the ARPAnet -- the world's first multiple-site computer network -- was created in 1969.