The first-ever trial of the International Criminal Court is set to start in The Hague on Monday.
Former Congolese military leader Thomas Lubanga is accused of war crimes for using child soldiers. He denies the allegation.
Mr Lubanga faces six charges of recruiting and using children to fight during the Democratic Republic of Congo's brutal five-year conflict that ended in 2003, the BBC reports.
Prosecutors say child soldiers were used to kill members of a rival ethnic group, or as Mr Lubanga's bodyguards.
The case is the first to come to trial before the ICC in The Hague.
This follows a seven-month delay, as judges and prosecutors at the world's first permanent war crimes court disputed confidential evidence.
Mr Lubanga, who is expected to enter not-guilty pleas, insists he was trying to bring peace to Ituri, a region in eastern Congo wracked by years of conflict between rival groups seeking to control its vast mineral wealth.
He was the leader of the Union of Congolese Patriots and its armed wing at the time of the alleged crimes in 2002-2003, and still has strong support among his Hema community in Ituri.
The prosecution says children had been snatched as they walked to school and forced to fight for Mr Lubanga's Hema militia against their Lendu rivals.
Many were plied with marijuana and told they were protected by witchcraft, according to human rights groups.
More than 30,000 children were recruited during the fighting which saw some 60,000 people lose their lives.