Fangak, South Sudan – The newest African nation is four years old. The government of South Sudan is due to mark this anniversary with a large and lavish celebration in the capital city of Juba on July 9.

President Salva Kiir’s photos fill billboards across Juba, proclaiming peace in a united country. But South Sudan has been convulsed by civil war since December 2013.

Military assaults on opposition-held territory since the end of April have been described by the UN as reaching a “new brutality and intensity”. Civilians are suffering tremendously at the hands of the army and militias.

Tens of thousands of families are sheltering in the vast swamplands of northern Jonglei state with limited access to food and medicine, after the army swept through neighbouring Unity state in May, leaving destruction in its wake.

Women and children describe journeys of many days in which they waded neck-deep through waterways and were shot at in the water by armed men as they fled.

The vast, thick swamplands act as some protection for the internally displaced families (IDPs) from future military incursions, but also mean it is difficult for humanitarian organisations to reach them with aid.

Access can only be gained by air, and crisis response teams are conducting emergency operations to bring assistance to the growing population of IDPs in this part of Jonglei.