(CNN) -- The International Criminal Court handed down its first-ever sentence Tuesday, sending Thomas Lubanga -- the Congolese warlord convicted of using child soldiers and turning them into killers -- to prison for 14 years.
But six years, from March 2006 until Tuesday, that Lubanga had been in custody will be deducted from the sentence, Judge Adrian Fulford at the court The Hague, Netherlands, said.
Fulford said "vulnerability of children mean that they need to be afforded particular protection that does not apply to the general population."
Lubanga's cooperation with the court was one of the mitigating factors that the court considered during sentencing, he said.
In March, the court convicted Lubanga of conscripting and enlisting children under age 15 and using them to participate in "hostilities" during a civil war in the Democratic Republic of the Congo.
Prosecutors said Lubanga led a rebel force that recruited child soldiers. The violence occurred between 2002 and 2003 in the mineral-rich eastern part of the nation.
Lubanga forced some of the child soldiers to serve in militia roles, including as his bodyguards, the court said.
Former child soldiers testified that Lubanga recruited them to kill, rape and rob.
Lubanga's case marked the ICC's first trial and first verdict since the court was established in 2002 to address offenses of international concern, such as genocide and war crimes.
In recent months, the court has come under fierce criticism that it disburses justice selectively.
Critics have said the court targets Africa and bypasses opportunities to investigate abuses in various nations, including Afghanistan and Iraq.
The court currently has investigations in the Central African Republic, Uganda, Kenya, Sudan, Ivory Coast and Libya.
CNN's Faith Karimi contributed to this report.