The great Prussian military theorist Carl von Clausewitz, in his classic On War, introduced the idea of friction in war. Friction was one of the most important ideas that Clausewitz put forward. His application of the term is generally taken to be limited to events on the field of battle. But had Clausewitz lived to the end of the 20th century, he undoubtedly would have broadened his understanding of friction to include the nexus between...