The conviction of Mr. Bemba — who was far from the battleground while his militia committed its crimes — was noteworthy in a second respect: It was the first time the court had applied the principle of command or superior responsibility. The judges found that Mr. Bemba was culpable for having “failed to prevent” the crimes committed by his subordinates, and for doing nothing to punish the offenses.

The judges on the panel were all women. The presiding judge, Sylvia Steiner of Brazil, read a summary of the verdict, noting crimes like the gang rape of women and girls as young as 10. Some were assaulted in the presence of family members and other children, she said.

Mr. Bemba’s case was taken up by the International Criminal Court at the request of the government of the Central African Republic, where the justice system lacks the ability to prosecute him. The country does not have a witness protection program that could shield rape victims and help ensure their cooperation.

Advocacy groups applauded the conviction for its focus on large-scale rape, among them Physicians for Human Rights. “The stigma and shame of this crime is moving where it belongs: to the perpetrator rather than the victim,” the group said in a statement.

Géraldine Mattioli-Zeltner, international justice advocacy director at Human Rights Watch, said the verdict offered “a stark reminder to commanders — military and civilian — that they are responsible for preventing and halting any attacks by their forces on civilians and for punishing violators.”