During World War II, Tonj served as a source of strength for the British Empire in Africa - not through soldiers, particularly, but through food. The Jur River (Luo River) chiefs contributed smoked meat for Allied forces fighting in North Africa, and thousands of cattle were driven out of the region to supply the front. In 1944, as partial repayment for this support, the British government built the first colonial school in South Sudan in Tonj, called Princes School. Its headmaster was Eric Daniel, known locally as Makerdit. That school is one reason Tonj has an unusual density of educated leaders: the town has produced William Deng Nhial - one of the first South Sudanese intellectuals to argue publicly for southern self-determination - and John Garang de Mabior, who would lead the SPLA through the second civil war and become the first president of the autonomous Government of Southern Sudan. Sudan's Omar al-Bashir also studied here, an irony that history delivered without comment.

At Wanhalel, in Tonj South, Dinka elders drafted the customary laws now known as Ganuun Wanhalel - the framework of rules that governs marriage, compensation, inheritance, and dispute resolution across Dinka communities throughout South Sudan. This matters. South Sudanese law is pluralist: there is state law, inherited from British and Sudanese practice, and there is customary law, which in most rural areas is what actually decides disputes. The Wanhalel laws are, in a real sense, one of the foundational legal texts of Dinka civil life, drafted and refined in Tonj South over decades. The town's role as a legal center is less visible than its role as a market or a mission station, but it is no less consequential for the daily life of several million people.

John Lee Tae-seok arrived in Tonj as a South Korean Catholic priest in the late 1990s and spent the next decade transforming what he could touch. He worked at the leper colony there, running a small medical mission. He founded the Don Bosco Hospital. He started a school. And he formed South Sudan's first brass band - a group of Tonj orphans he taught to play instruments salvaged and donated from abroad, who became locally famous and gave Tonj a sound that distinguished it. When Lee died of cancer in 2010, he was mourned by a population that had come to see him as family, and the Korean public network KBS partnered with the South Sudanese government on a project called "Smile, Tonj" to rebuild what he had built. His story is the subject of school textbooks in both South Sudan and South Korea.

Tonj's relationship with education has continued to produce surprises. Tito Yak Kuol topped both the Kenyan primary and secondary leaving examinations and became the first South Sudanese student accepted to Harvard College. Emmanuel Malou Deng placed fifth in all of South Sudan in the national secondary examinations and went on to Columbia. Mary Nyanbul Gum placed second in the entire Sudan in the 2013 Sudan School Certificate of Secondary Education - the first South Sudanese woman to crack the top ten nationally - and graduated from Brown University in 2020. Albino Akol Atem placed tenth in the same Sudanese examination. Emmanuel Jal, born in Tonj, was forcibly conscripted as a child soldier during the civil war and rebuilt himself into an internationally recognized musician, actor, and activist. The town is divided into Tonj North, Tonj South, and Tonj East counties; its families are from the Dinka, Bongo, and Luo peoples; and its children, again and again, turn academic results into passports out of the war-marked country they love.