Answer: barbedwire

AnswerCrossword Clue
BARBEDWIRERange barrier
BARBEDWIRELucien B. Smith's invention: 1874
BARBEDWIREFrontier border protection
BARBEDWIRESarcastic telegram
BARBEDWIREGlidden's invention: 1873
BARBEDWIREMaterial that reinforced the top of the Berlin Wall: 2 wds.
BARBEDWIREJoseph Glidden's 1874 good idea
BARBEDWIREPrison camp barrier