Wont start..like i have NO battery

1965 Dart, started up fine, drove around the block a few times..depressed the brake pedal to slow down and turn around...everything shuts off. Ok, put in park, turned the key..and nothin!!! WTF!!! Its like someone took the battery out..but the battery is fine..so i dont know if its a fuse..some electrical crap or i just totaly messed this thing up. It is parked now in the yard, and Im not around to look at it..but i did look at the 6 fuses under the dash and they all look fine...any other ideas?