This army runs on its fuel supply

By CHARLES ARTHUR in London

Modern armies do not march on their stomachs; they drive on their fuel tanks. That is a particular concern for the United States Army, which has hundreds of Abrams M1 tanks in the field - each typically consuming around 720 litres of kerosene-grade diesel fuel every 100km, and with a "cruising range" of up to 440km on a single 1900-litre fuelling.

The 120 British Challenger tanks are less thirsty, consuming around 220 litres per 100km.

On their own the tanks now in action are burning nearly 1.6 million litres of fuel every day - equivalent to about 100 jumbo jets.

Add in the requirements of hundreds more Humvee trucks and Bradley armoured vehicles and the US and British armies' needs are clear: fighting in the desert doesn't leave just the humans thirsty.

This war may not be being fought over oil, but it is certainly being fought on aircraft-grade kerosene: on the American side, a mixture known as "JP-8" which is almost identical to aviation-grade kerosene and can be used in both air and ground equipment.

With roughly 3.7 million litres of JP-8 being required every day, the logistics of a 480km "dash to Baghdad" come into sharp relief. To feed the tanks and armoured vehicles, the US has set up 23 military fuel dumps throughout the Middle East containing millions of litres of JP-8. They have been stocked up in a logistics exercise running alongside - and before - the more visible troop buildup.

Every day thousands of litres of JP-8 are flown in by helicopter and in aircraft drops; the tanks are refuelled either by tanker trucks, or (more inventively) by a "bladder" that is filled with fuel and placed on the ground, with an inlet to the tank, which then rolls slowly over it to squeeze the fuel out and into its fuel reserve.

But what is provided is still not enough. While the US may deny any "operational pause" in the present campaign, a logistics analysis of the 1991 Gulf War - for which there was a six-month logistics and troop buildup - by Lieutenant-Colonel Christopher Paperone, who served in the 18th Airborne Corps, notes that "had the ground war exceeded 100 hours, the XVIII Airborne Corps (and hence the coalition forces) would have needed an unplanned operational pause to allow logistics to catch up to the combat advance".

Having carefully analysed their failings the last time, this time the logistics side was more successful: it was seven, rather than five, days before the US troops outran their support lines.

JP-8 was developed in the 1980s because the US military and Nato realised that having to provide different grades of fuel to different vehicles was both a logistical nightmare, and potentially disastrous.

The historical lesson for this also comes from the desert, from Rommel's defeat. On paper the Afrika Korps was better-led with more experienced fighters. But it lost to the British Eighth Army because the German and Italian vehicles needed different types of fuel, and kept outrunning their supplies. They lost behind their own lines.

Yet JP-8 is not the ideal fuel, except in logistical terms. Previous Gulf operations - Desert Storm and Desert Fox - where it was used showed that it reduced the Abrams tanks' already poor fuel efficiency further.

Gas guzzlers

* US Abrams tank uses 720 litres per 100km (3 gallons per mile)

* British Challenger tanks consume around 220 litres per 100km

* Coalition tanks are using 1.6 million litres a day

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Herald Feature: Iraq war