"The first duty of the command and control system is to survive," Baran argued, proposing a distributed network with hundreds or thousands of separate nodes connected through multiple paths. Messages would be broken into smaller "blocks," sent along the first available path, and reassembled at their final destination. If nodes were out of service or destroyed, the network would automatically adapt and send the data along a route that was still intact. Baran's work later provided the conceptual basis for the top secret communications networks at the Pentagon, as well as their civilian offshoot, the Internet."