Gbagbo becomes the first ex-head of state to stand in the dock at the International Criminal Court (ICC) in The Hague, in a case which will test the tribunal's avowed aim to deliver justice to the victims of the world's worst crimes.
Prosecutors accuse the one-time west African strongman of devising a plan to cling to power in the world's top cocoa producer after being narrowly defeated by his bitter rival Alassane Ouattara in November 2010 elections.
Both the prosecutors and defence lawyers vowed on the eve of the trial -- which could last three to four years -- that they will seek to lift the veil on the bloody five-month crisis.
"The purpose of the trial is to uncover the truth through a purely legal process," said ICC chief prosecutor Fatou Bensouda.
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Abidjan, one of Africa's most cosmopolitan cities, was turned into a war zone between 2010 to 2011 as clashes flared between the rival forces in a deadly power struggle.
Gbagbo's defence lawyer, Emmanuel Altit, insisted on Wednesday that it was "an important trial for Cote d'Ivoire and for Africa" and would help "clarify and understand the tragic events that occurred in that country."
Gbagbo's supporters accuse Paris of plotting to oust him, and charge that Ouattara's camp has not been investigated for also carrying out a string of abuses.
Prosecutor Bensouda said her investigations into other crimes committed during that period were launched last year and "intensifying."