More than 3,000 were killed in the September military onslaught, which began when fighter jets bombed the Presidential Palace while the democratically elected President, Salvador Allende, was still inside.
It was the start of a 17-year rule by General Pinochet. But the bloodshed did not stop there.
The general looked fearsome and talked tough. He promised wholesale reform of the political system which had allowed the annual rate of inflation to reach 150% in 1973.
No time was wasted. The military government dissolved Congress, suspended the constitution and opposition parties were outlawed. Shortly after came a night-time curfew and strict limits on the media.
Economic reform came in the shape of free-market principles. Nationalised companies were returned to their original owners, trade barriers were cut to encourage foreign imports and there was renewed emphasis on exports.
General Pinochet had once articulated his goal as "to make Chile not a nation of proletarians, but a nation of entrepreneurs".
Chilean society had been split by Allende's socialist rule, and so it was under the new right-wing leader. But with Pinochet in charge dissidents spoke out at their peril.
The general's iron rule was underpinned by the tactics of brutal repression that saw thousands die and thousands more flee into exile. Others disappeared or were tortured.
Particular targets were those who threatened unrest in the workplace and the shantytown dwellers who demanded better living conditions.
In the absence of any official political opposition, the Roman Catholic Church assumed the role of moral critic.
In 1976 the Pinochet regime's anti-democratic tactics were glimpsed by the wider world when a former Allende ambassador to the US was killed by a car bomb in Washington DC.
There was little doubt that the murder was linked to the government in Santiago but attempts by the Americans to extradite the accused members of the Chilean military were reportedly rebuffed.
Ten years later General Pinochet himself was the target of an assassination attempt, by the armed wing of the Communist Party. The dictator, however, escaped the attack on his motorcade with a few minor injuries.
When in 1990 he stepped down, it was due to his own miscalculation. He gambled his one-man rule on a plebiscite and lost.
The general was down but not out. The constitution he had been instrumental in drawing up guaranteed his continuation as army commander-in-chief until 1998.
He has ensured the armed forces remain largely outside the control of the government - a condition that has made it difficult to bring the military to book for past human rights offences.