On Saturday, the Syrian Democratic Forces raised their bright yellow banner from a shell-pocked house where ISIS militants once flew their notorious black flag.

The “Caliphate's" end also marks a new phase in Syria's war, as the SDF commander Mazlum Abdi said in a ceremony at al-Omar oil field base.

Speaking at the ceremony senior U.S. diplomat, William Roebuck, said the territorial defeat of the Islamic State group is a "critical milestone" that delivers a crushing and strategic blow to the extremist group. He also underlined that ISIS remains a significant threat and added: "We still have much work to do to achieve an enduring defeat of ISIS.”

SDF commander Mazlum Abdi appealed for continued assistance to his group until the full eradication of the extremist group.

The site of ISIS' last stronghold was a tent camp in Baghouz where thousands of civilians were holed up. During the SDF weeks-long campaign to free Baghouz, some 30,000 men, women and children were evacuated from the pocket, most of them ISIS family members, a mix of Syrians, Iraqis and foreigners. They were exhausted, hungry, wounded and traumatized. Most were taken to al-Hol camp in Hassakeh province, under the supervision of the Northern and Eastern Syria Autonomous Administration.

On Saturday, journalists were taken to the camp.

Ciya Kobani, an SDF commander, announced the end of the operation from the roof of the building with the SDF flag: "We have been victorious against Daesh," he declared.

At its height, the Islamic State had occupied around a third of both Syria and Iraq, holding millions hostage to its harsh and violent interpretation of Islamic law.

Sieged in Baghouz, ISIS fought fiercely and desperately to hang on to the last stronghold using thousands of civilians, including women and children, as human shields.