A former Congolese rebel leader has been found guilty of war crimes and crimes against humanity.
Fighters loyal to Bosco Ntaganda disembowelled babies and smashed their heads in, said judges at the International Criminal Court (ICC).
In all, Ntaganda, nicknamed "Terminator", was convicted on 18 counts, including murder, rape, sexual slavery and using child soldiers.
He becomes the first person convicted of sexual slavery by the ICC.
His lawyers had argued that Ntaganda was a victim, having also been recruited as a child soldier.
He is the fourth person convicted by the ICC since its creation in 2002.
Ntaganda surrendered at the US embassy in in the Democratic Republic of Congo in 2013.
Analysts said it was an act of self-preservation, motivated by the danger he was in after losing a power-struggle within his M23 rebel group.
A three-judge bench found Ntaganda guilty on all 18 counts of war crimes and crimes against humanity committed in the mineral-rich eastern region of Ituri between 2002 and 2003.
Ntaganda, 46, was a "key leader" who gave orders to "target and kill civilians" judge Robert Fremr said in the ruling.
Prosecutors had said Ntaganda was key in planning and running operations for the Union of Congolese Patriots (UCP) rebels and its military wing, the Patriotic Forces for the Liberation of Congo (FPLC).
The armed group conducted attacks against people perceived not to belong to the Hema ethnic group, the ICC found.
In one attack, fighters killed 49 captured people in a banana field behind a village using "sticks and batons as well as knives and machetes".
"Men, women and children and babies were found in the field. Some bodies were found naked, some had hands tied up, some had their heads crushed. Several bodies were disembowelled or otherwise mutilated," Judge Fremr said.
The judges ruled that Ntaganda had personally killed a Catholic priest, while the fighters he commanded ran rampage in the region.
The crimes took place when Ntaganda served as the deputy chief of general staff of Thomas Lubanga - who was the leader of the UCP. He was the first person to be convicted by the ICC in 2012 and sentenced to 14 years.
By Anna Holligan, BBC News, The Hague
Forty-nine mutilated bodies strewn in a banana field. A pregnant woman killed while trying to shield herself from rape. Children under the age of 15 conscripted to fight - women and girls kept as sex slaves.
In court, judges highlighted the horror brought by Bosco Ntaganda's rebel forces before finding the 46-year-old guilty of all 18 charges.
His lawyers had argued he too was a victim, kidnapped as a child and trained as a soldier before becoming the first suspect to voluntarily surrender to the ICC - this was deemed no excuse for ruthless attacks committed in adulthood.
More than 2,000 survivors were cleared to take part in this trial. Human rights groups said this judgment provided an important measure of justice.
Ntaganda fought under the command of Rwanda Patriotic Front (RPF) leader, now Rwandan president, Paul Kagame to end the 1994 genocide against his ethnic group - the Tutsi.
After Rwanda's unrest spilled over into neighbouring DR Congo, he started to flip between fighting rebellions and serving in national armies - both Rwandan and Congolese.
In 2012, he became the founding member of the M23 rebel group after he defected with hundreds of soldiers from the Congolese national army.
His fighters later took over DR Congo's eastern city of Goma before agreeing to withdraw. At least 800,000 people reportedly fled their homes.
The M23 rebel group was eventually defeated by Congolese government forces in 2013.