Groups aligned with the South Sudanese military reportedly committed sexual violence against boys and girls over a period of several weeks in May 2015 in Unity state. In a story by the AP:
At least 129 children were killed, with boys castrated and girls raped, during a government offensive against rebels last month in South Sudan, according to the U.N. children's agency.
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...UNICEF Executive Director Anthony Lake said survivors reported that boys were castrated and left to bleed out, while girls were gang raped and killed.
Other children were thrown into burning buildings, he said...
According to an article in Christian Today, this information was given to UNICEF by civilian witnesses and survivors who made it to the UN base in Bentiu, a city where tens of thousands of South Sudanese were seeking shelter. The witnesses said that the attackers did not want the children to grow up and exact revenge for the crimes they suffered in the civil war, so the attackers decided to kill the children – even including newborns. Nonetheless, some children were reportedly taken into slavery: boys as soldiers, girls as wives.
"UNICEF: 129 children killed in South Sudan fighting in May." AP, published by Fox News, June 18, 2015.
"Slaughter in South Sudan: Girls raped, boys castrated, newborns killed in civil war, UNICEF says." Monica Cantilero, Christian Today, June 22, 2015.