Iraqi President Saddam Hussein had a plan to take on the might of the United States: fight dirty and fight in urban areas to grind down a casualty-averse nation still haunted by the horror of 'Black Hawk Down'.

For a brief moment after the war started, it looked like his strategy was working. One commander grumbled that he hadn't wargamed for what he found on the battlefield and critics in Washington were warning of another Vietnam.

But it was just a brief moment.

Many Iraqi soldiers fought valiantly -- as history has shown they can -- and they had learnt new tactics since their thumping in the open desert in the 1991 Gulf War. But they were woefully bad at organising themselves into a coherent fighting force.

"Individual people have shown a degree of professionalism, but collectively there was no mechanism for coordination," said Andrew Brookes of the International Institute for Strategic Studies. "I put that down to the fact that communications were shattered between everyone."

Iraq started out with a formidable disadvantage despite its overwhelming advantage -- at least on paper -- in numbers. It had old weapons and tanks and its troops were poorly motivated and disciplined.

Command and Control Uprooted

But the course was set from the very start when US and British forces used their air supremacy to uproot Iraq's command and control, leaving even the elite Republican Guard, who had been drawn back for a showdown at the gates of Baghdad, in doubt and disarray.

"What the attackers were therefore dealing with were isolated pockets of people who resisted out of either loyalty to the regime or wanting to oppose an invading force," said Ivo Daalder at the Brookings Institution in Washington.

"But it was nothing coordinated. The bombing around and in Baghdad left the Republican Guards without coherence and what the Iraqis were left with were irregular forces, or regular forces who became irregular. In many instances they ran away."

Kenneth Pollack of the Saban Centre for Middle East Policy said Iraq had latched onto America's bloody tangle in Mogadishu 10 years ago, when ragtag Somali forces downed a US helicopter and attacked troops sent to rescue the pilots.

The experience -- etched onto the American psyche by the movie 'Black Hawk Down' -- was something the Iraqis had hoped to recreate many times over by using irregular forces and tactics.

But Pollack said in a briefing paper that the 'unsophisticated copying' of the Somali experience had not taken into account the unique circumstances that Iraq found itself in.

Using civilians as human shields may have had some effect, but taking on Abrams tanks with machine guns and grenade launchers mounted on pickup trucks was quite simply hopeless.

Iraq's military history has demonstrated that its troops are capable of fighting ferociously in static defensive positions and straightforward attacks, Pollack said.

But this -- as with its plan to fight dirty -- proved to be of little use against US forces who excel in fluid battlefield conditions, manoeuvre warfare and combined arms operations.

What Happened to the Republican Guard?

If there were two big surprises delivered by Iraq they were the trouble it gave US-led forces with irregular forces such as fidayeen, particularly in the south, and the failure of its 70,000-strong Republican Guard to put up a better fight.

Although there is still one division of the Republican Guard defending Saddam's hometown in the north, Tikrit, two were torn to shreds as the US forces closed in on Baghdad and the others faded away.

Andrew Denison, a foreign policy and security analyst at Transatlantic Networks, said the Republican Guard proved easy prey as long as they were in the field and they would have been less vulnerable if they had backed into an urban landscape.

"Why were they so exposed?" he asked. "Possibly Saddam feared some generals might try to topple him, there have been attempts in the past.

"That left just the Special Republic Guards in the city. They are loyal to the point of fanaticism, but they are not necessarily that good. Promotion is secured more by loyalty than performance."

Lawrence Korb, a former assistant US defence secretary and now a senior official with the private Council on Foreign Relations in New York, said the Republican Guard collapsed because they had an overblown sense of self-worth.

He believes they found themselves vulnerable to airpower and unable to back into Baghdad in an organised way because they had an exaggerated sense of their own capabilities, something that was fed by public statements of confidence from people like the information minister.

"And the other reason… was that even though Saddam wasn't killed on the first night it was clear that he was pretty well shaken up," Korb said. "There didn't seem to be anybody in charge of the overall operation."

(Additional reporting by Charles Aldinger in Washington, Paul Majendie in London and Philip Blenkinsop in Berlin)