By Gary Eason
BBC News Online
More than ever before, the war in Iraq was a conflict won by precision guided munitions - "smart" bombs.
Although the rapid advance by the ground forces proved decisive, their way was paved by the aerial bombardment of Iraqi command systems and army divisions.
The man in charge of the coalition air effort, US Air Force Lieutenant General Michael Moseley, said of reports that the bombing was "softening up" the Republican Guard south of Baghdad:
"We're not softening them up, we're killing them."
Above all this was a JDam war.
JDam is the joint direct attack munition: an ordinary 1,000 lb or 2,000 lb bomb made "smart" by the strapping on of a tail kit.
The kit gives the bomb manoeuvring fins controlled by satellite and inertial guidance systems.
This turns it from a flying lump of high explosive into a precision weapon with an accuracy of 40 feet or better.
JDams and other precision weapons gave mission planners two great advantages:
Colonel James Kowalski, commander of the 405th Air Expeditionary Wing of B-1B bombers, called JDams "our weapon of choice".
- reduced risk of hitting the area around the intended target - the feared "collateral damage"
- the ability to use far fewer bombs to be sure of destroying a given location.
"It's an all-weather weapon. It has proven reliability and it packs a big punch.
"And when you mate it up with a B-1 that can carry 24 of them and then basically range across Iraq, you can hold at risk just about any target in the country."
One thing that has been in short supply however is a flow of information on what the weapons were hitting, other than in some specific cases.
Colonel Kowalski said events had moved so fast that the normal process of checking that weapons had detonated where they were supposed to had been a less than precise science.
But when they had got images back, JDams had been performing "well above 99%".
Another advantage is their relatively low cost - about $20,000 apiece.
At the opposite end of the spectrum - at more than $1m each - were the cruise missiles, launched into Iraq mostly from US guided missile destroyers and cruisers in the Gulf.
By the end of hostilities more than 750 of these had been used.
The first shots on Baghdad came from two F-117 stealth fighters with "bunker busting" 2,000 lb bombs.
These were of a type never before used: EGBU-27 "enhanced" laser-guided bombs, which have added satellite and inertial navigation.
The RAF also rushed into service a new weapon - another bunker buster, the Storm Shadow air-launched cruise missile. At least 30 were used.
And US bombers used new, more accurate CBU-105 anti-armour cluster bombs - which have tail kits that correct for wind drift - against Iraqi tanks south of Baghdad.
In total, some 70% of the weapons used against Iraq were precision-guided of one sort or another - more than 18,000 in all.
But in other words, almost a third were not - so there was still a significant role for the extensive arsenal of "dumb" bombs.
On one occasion, for instance, a B-2 stealth bomber that had flown all the way from its base in Missouri in the USA - a 34-hour round trip - dropped no fewer than 80, 500-lb general purpose bombs in one go on an Iraqi garrison.
Being in control
On the ground the US M1 Abrams and British Challenger 2 tanks, though far from impregnable, proved overwhelmingly superior to the older Iraqi T-72 and T-55 machines.
The army and marines were also given valuable additional firepower by the Apache and Cobra attack helicopters they had with them.
But there was another key element in the coalition armoury - which, just as crucially, was lacking or quickly destroyed on the Iraqi side: C4ISR.
This acronym, unwieldy even by military standards, stands for command, control, communications, computers, intelligence, surveillance and reconnaissance.
In other words, the ability to know what is going on and to organise events.
In the air over Iraq there were coalition surveillance planes operating around the clock to give commanders a visual and electronic picture of the ground.
More than 50 satellites were available, partly to control the GPS-guided weapons and partly to provide images of the ground.
Similarly, "forward air control" planes were operating 24 hours a day, liaising with ground forces, to guide attack jets onto their targets.
The bombers and fighter-bombers from five aircraft carriers and eventually more than 30 airfields were stacked up in the air with a mix of weapons, co-ordinated by Awacs flying control centres.
All this was made possible by the constant presence of airborne refuelling tankers.
And it did not just happen - it had been extensively rehearsed over several years.
US Airforce General Moseley said: "We have really thought this through to make it the best joint and combined American and coalition effort that we can."
Getting control of the airspace over Iraq was made easier by some 4,000 days of experience of operating the "no-fly zones" over northern and southern Iraq.
The US and Britain used this time to identify and attack Iraq's air defence radars and missiles, stepping up that campaign in 2002.
They had also taken the opportunity to amass detailed intelligence about the location of potential targets in Iraq - the key to the use of the precision weapons.
Another aspect of the coalition forces' technical superiority was that they "owned the night" - being able to operate in the dark thanks to night-vision goggles and, in the air, compatible cockpits.
The importance of this to their effort was clear when US Defence Secretary Donald Rumsfeld accused Syria of at least failing to prevent the smuggling into Iraq of military supplies, said to include night-vision goggles.
This night capability was especially vital to special forces troops on the ground all over Iraq.
Numerous special forces provided targeting information for the aircraft, seized key locations, worked with Kurdish fighters in the north and fought their own, often fierce battles out of the media spotlight.
Though not obviously a weapon, there seems to have been an important role for "psy-ops" - psychological operations.
The oil industry is your livelihood, leaflets warned
More than 43 million leaflets were dropped on Iraq before and during the fighting, for instance.
It seems many Iraqi soldiers "got the message" and simply went home, rather than fighting.
One surprise was that the coalition forces managed to capture southern oil fields more or less intact early on in the invasion, one of their key objectives. It had been expected they would be sabotaged.
US Central Command's director of operations, Major General Gene Renuart, said many of the wellheads had indeed been wired with explosives - but these had not gone off and even if they had done so, the oil pipeline valves had been shut.
He said that when Iraqi oil workers were interviewed about this, they replied: "We read your leaflets. We heard your broadcasts. We understand that keeping the oil infrastructure was important for our future.
"And so while we complied for our own protection with the regime, we ensured that true damage to the oil fields would not occur."