A presidential decree in Iraq divided the country up into four military zones ahead of the US-led war.
BBC News Online looks at the men in charge of defending Iraq against the military onslaught.
Saddam Hussein's decree outlined plans to "to confront and destroy any foreign aggression".
The president retains control of the air force, gunship corps and surface-to-surface missiles. Four regional commands report directly to Saddam Hussein.
The south: General Ali Hassan al-Majid
General Majid, a cousin of Saddam Hussein, is known as "Chemical Ali" for his role in the attacks on Kurds in northern Iraq in 1988 in which an estimated 5,000 people were killed in a single day.
The BBC's Andrew Gilligan in Baghdad says the appointment of General Majid to command the southern region and the city of Basra could be aimed at intimidating US and UK troops expected to invade that area.
General Majid: Also known as Chemical Ali
He was initially "governor" of Kuwait after the 1990 invasion.
General Majid is accused by the US of taking part in the repression of the uprisings by the Kurds and the Shias after the 1991 Gulf War.
He is a member of the key Revolution Command Council and a dependable ally of the Iraqi leader, unlike a number of other members of Saddam Hussein's clan who have, fatally for some of them, fallen out of favour at different times.
The north: General Izzat Ibrahim
General Ibrahim, Vice-President Taha Yasin Ramadan and Saddam Hussein himself are the only survivors from the plotters who carried out the 1968 coup which brought the Baath Party to power.
General Ibrahim serves as the Iraqi leader's number two in the regime's powerful Revolution Command Council, as vice-chairman.
General Izzat Ibrahim: Second in command on the Revolutionary Command Council
His daughter was briefly married to Saddam Hussein's elder son, Uday.
When the Gulf War broke out in 1991, The New York Times newspaper quoted General Ibrahim as warning the Kurds not to cause trouble.
He reminded them of the chemical attack with the words: "If you have forgotten Halabja, I would like to remind you that we are ready to repeat the operation."
He has exchanged an embrace with Crown Prince Abdullah of Saudi Arabia and has promised to respect the "territorial integrity" of Kuwait.
He narrowly escaped arrest on a war crimes warrant in Austria once while being treated for suspected cancer.
Central region: Saddam Hussein's son Qusay
Qusay, 36, is the younger of Saddam Hussein's two sons.
He is presumed to be heir apparent and has been put in charge of defending the central area of the country including Baghdad and Saddam Hussein's hometown Tikrit.
He also runs the elite Republican Guard - Iraq's best trained and equipped army unit entrusted with the protection of the president.
And he controls the internal security and intelligence, including the Special Security Organisation, the secret police which has suppressed opposition to the regime.
Father and son: Qusay has been given a crucial role in Iraq's defence
Commentators also say Qusay has increasingly taken a leading role in the country's foreign affairs, and is thought to have spearheaded Iraq's attempts to rebuild ties with its Arab neighbours.
In May 2001, Qusay was given a leading position in the ruling Baath party. Many commentators in the Arab world cited this move as a clear sign that the struggle for the succession had been decided in his favour.
Reports in the Western press in 2002 claimed that Saddam Hussein had considered formally handing over control to his younger son to counter the threat to his regime from the US administration.
Central Euphrates region: Mizban Khadr Hadi
A little-known member of the ruling Revolutionary Command Council, Mizban Khadr Hadi, will control the central Euphrates area, which includes the Shia holy sites in Karbala and Najaf.
Some analysts have predicted an uprising in this region once war is under way. In 1991 Shia Iraqis rebelled and were brutally put down.