> Rumors had persisted for years that the ARPANET had been built to protect national security in the face of a nuclear attack. It was a myth that had gone unchallenged long enough to become widely accepted as fact.

No, the Internet (inclusive of ARPANET, NSFNet, and so on) was not designed to survive a nuclear war. It's the worst kind of myth: One you can cite legitimate sources for, because it's been repeated long enough even semi-experts believe it.

The ARPANET was made to help researchers and to justify the cost of a mainframe computer:

> It's understandable how it could spread. Military communications during Nuclear War makes a more memorable story than designing a way to remote access what would become the first massively parallel computer, the ILLIAC IV. The funding and motivation for building ARPANET was partially to get this computer, once built, to be "online" in order to justify the cost of building it. This way more scientists could use the expensive machine.