Actually, it seems ARPANET was not designed to survive nuclear war:
http://www.internetsociety.org/internet/what-internet/histor...
> It was from the RAND study that the false rumor started claiming that the ARPANET was somehow related to building a network resistant to nuclear war. This was never true of the ARPANET, only the unrelated RAND study on secure voice considered nuclear war. However, the later work on Internetting did emphasize robustness and survivability, including the capability to withstand losses of large portions of the underlying networks.
Charles Herzfeld, ARPA Director (1965–1967), said:
http://inventors.about.com/library/inventors/bl_Charles_Herz...
> The ARPANET was not started to create a Command and Control System that would survive a nuclear attack, as many now claim. To build such a system was, clearly, a major military need, but it was not ARPA's mission to do this; in fact, we would have been severely criticized had we tried. Rather, the ARPANET came out of our frustration that there were only a limited number of large, powerful research computers in the country, and that many research investigators, who should have access to them, were geographically separated from them.
Paul Baran:
http://www.wired.com/wired/archive/9.03/baran.html
> Wired: The myth of the Arpanet - which still persists - is that it was developed to withstand nuclear strikes. That's wrong, isn't it?
> Paul Baran: Yes. Bob Taylor had a couple of computer terminals speaking to different machines, and his idea was to have some way of having a terminal speak to any of them and have a network. That's really the origin of the ARPANET. The method used to connect things together was an open issue for a time.