The former Bosnian Serb commander Ratko Mladic was accused of intending to ‘ethnically cleanse’ Bosnia of Bosniaks and Croats, the court heard on the first day of his trial.
Mladic is charged with 11 counts of war crimes and crimes against humanity and genocide.
The former army general is accused of commanding Serb troops who killed over 8000 Bosniak men and boys in Srebrenica in 1995 and in connection with the 44-month siege of Sarajevo during which over 10,000 people died.
"Four days ago marked two decades since Ratko Mladic became the commander of the main staff of the army of Republika Srpska - the VRS," said prosecutor Dermot Groome.
"On that day, Mladic began his full participation in a criminal endeavour that was already in progress. On that day, he assumed the mantle of realising through military might the criminal goals of ethnically cleansing much of Bosnia. On that day, he commenced his direct involvement in serious international crimes."
Mr Groome said the attacks by Mladic’s forces where part of a systematic plan to ethnically cleanse non-Serbs from majority-Serb parts of Bosnia.
Mr Groome said crimes of sexual violence were integral to the process of "taking over and ethnically cleansing Bosnia".
"While women were most often targeted for such crimes of terrible violation, men were also victims," he said.