[1] Led by Yoanis Okiech, the TFNF originally split from the Sudan People's Liberation Army (SPLA) in late October 2015 and subsequently started an insurgency against the SPLM government.

Okiech initially remained loyal to the government when Shilluk elements in the SPLA, most notably John Uliny's Agwelek forces, rebelled in May 2015.

Nevertheless, the government did not trust him and put him under house arrest while his troops remained in Manyo County in northern Upper Nile State, from which they had driven SPLM-IO rebels in early 2015.

Attacking loyalist forces at Wadakona, Gabat, Mananmand Ajot, Nyanowar, and Tor Gwang, the TFNF expanded its area of control.

Although the Tigers were not powerful enough to capture the strategically significant town of Renk, they controlled much of northern Western Nile State by early 2016, also thanks to widespread support by local Shilluk civilians.

[2][10] In January 2017, the SPLM-IO forces in Western Upper Nile launched a major campaign against the local NDM affiliates, leading to fierce clashes between the two sides in the area around Hamra,[11] a small village near Kodok.

[5][12][13] John Uliny's men continued to pursue him, and eventually cornered Okiech at Thoroji, in northern Upper Nile near the border to Sudan.