As deputy to the ailing General Bakr, Saddam Hussein instituted widespread reforms and built up a ruthless security apparatus.
The two leaders' early moves caused concern in the West.
In 1972, at the height of the Cold War, Iraq signed a 15-year treaty with the Soviet Union.
It also nationalised the Iraqi Petroleum Company, which had been set up under British administration and was pumping cheap oil to the West.
Soaring oil revenues resulting from the 1973 oil crisis were invested in industry, education and healthcare, raising Iraq's standard of living to one of the highest in the Arab world.
In 1974, Kurds in the north funded by the US-backed Shah of Iran rebelled.
The conflict pushed Baghdad to the negotiating table, where Iraq agreed to share control of the disputed Shatt al-Arab waterway with Iran.
The Shah cut off the Kurds' funds and the Iraqi regime put down their uprising.
Saddam Hussein extended his grip on power, stationing relatives and allies in key government and business roles.
In 1978, membership of opposition parties became punishable by death.
The following year, Saddam Hussein forced General Bakr's resignation - officially due to ill health - and assumed the presidency.
He executed dozens of his rivals within days of taking power.