American forces in Iraq are in danger of having their line of supply cut by guerrillas. Napoleon once said that "an army travels on its stomach." By that he meant that the problem of keeping an army supplied is the prerequisite for the very existence of the force.
A 21st-century military force "burns up" a tremendous volume of expendable supplies and continuously needs repairs to equipment as well as medical treatment. Without a plentiful and dependable source of fuel, food, and ammunition, a military force falters. First it stops moving, then it begins to starve, and eventually it becomes unable to resist the enemy.
In 1915, for example, this happened to British forces that had invaded Mesopotamia. A British-Indian force traveled up the line of the Tigris River, advancing to Kut, southeast of Baghdad. They became besieged there after their line of supply was cut along the river to the south. Some 11,000 troops ultimately surrendered, after the allies suffered another 23,000 casualties trying to rescue them.
American troops all over central and northern Iraq are supplied with fuel, food, and ammunition by truck convoy from a supply base hundreds of miles away in Kuwait. All but a small amount of our soldiers' supplies come into the country over roads that pass through the Shiite-dominated south of Iraq.
Until now the Shiite Arabs of Iraq have been told by their leaders to leave American forces alone. But an escalation of tensions between Iran and the US could change that overnight. Moreover, the ever-increasing violence of the civil war in Iraq can change the alignment of forces there unexpectedly.