5 ideas
Netz reads modern history as a story about who can stop whom from moving, and where. Space is not neutral terrain. It is made political by barriers that sort bodies into inside and outside, allowed and forbidden. Seen this way, a fence is more than infrastructure. It is an argument about who gets to move.
Barbed wire does not physically block the way a stone wall does. It works by threatening pain, which teaches animals and people to avoid it. Deterrence replaces mass, so a thin, light, cheap material can control huge areas, and power becomes easy to industrialize and spread.
After 1874, mass-produced barbed wire let ranchers and farmers fence the treeless Great Plains, where timber and stone were scarce, bringing the open range to a close. Netz treats the slaughter of the bison and the conquest of Native peoples as distinct from this later fencing of cattle, which reshaped the prairie into bounded property within a few decades.
In the First World War, belts of barbed wire held attacking infantry in place while machine guns and artillery killed them. This made defense far stronger than attack. The resulting deadlock came less from strategy than from a cheap barrier that stopped human motion at the exact point where firepower was aimed.
Barbed wire made enclosure cheap and portable, which helped concentration camps, Nazi camps, and the gulag be set up quickly and at large scale. Netz does not claim earlier detention required masonry; wooden stockades and improvised sites existed before, and wire lowered the material cost of confinement further.