Inventor: Michael Kelly

After being originally introduced in France in 1860, the invention of barbed wire crossed the Atlantic, making its debut on American soil in 1867.  The first form was a single strand of wire with sharp barbs, but was later improved by the dual strand version patented by Michael Kelly in 1868.  The barbed wire was effectively used in fencing around farms to separate property, livestock, and crops

Although it was originally used for fencing, barbed wire was widely used for military reasons during World War I.  It was placed over trenches and other areas to provide defense against attacks.  In addition, today barbed wire can be found on all sorts of fences, such as prisons, as its usage isn't limited to farms anymore.

Picture from Encarta Encyclopedia

SOURCES:

"Barbed Wire". Microsoft Encarta Electronic Encyclopedia Edition 2002.

• A good source that discussed the history and usage of barbed wire