The Fog of Battle: Bush's diplomatic offensive is well underway. But talk is cheap, and war is not. Evaluating the military options.

Byline: John Barry and Evan Thomas

It was, in sheer scale, "the greatest cavalry charge in American history," wrote one military historian. The four-day, 250-mile sprint of the 24th Mechanized Division around the western flank of Saddam Hussein's Army in the 1991 gulf war was a dashing feat of arms, a show of American can-do spirit and ability. But as the U.S. military prepares to finish the job, possibly by driving all the way to Baghdad, it is worth considering the heavy lifting required to move a division of tanks and armored-personnel carriers that far, that fast. The 24th Mech had 1,600 armored vehicles, 3,500 wheeled vehicles and 90 helicopters. To keep the division's 18,000 soldiers rolling along required 395,000 gallons of fuel, 213,000 gallons of water and 2,400 tons of ammunition--each day. Before shoving off, the 24th Mech stockpiled 2.3 million gallons of fuel and 3 million tons of other supplies. Multiply those totals by four or five, and you have some idea of the bare minimum of logistics required by the Pentagon to fight a brief but winning war 8,000 miles away.

Diplomacy may head off war. Conceivably, Saddam will allow U.N. arms inspectors free rein to roam Iraq. But in the more likely event that the…