The early ZAR was poor, agrarian, and fiercely independent. Its first president, Marthinus Wessel Pretorius, was the son of the commander who had led the Voortrekkers to victory at Blood River. The capital moved from Potchefstroom to Pretoria, and a parliament called the Volksraad of two dozen members governed a citizenry that was, by law, white only. Military service rested on the kommando system: when danger threatened, able-bodied burghers rode out under officers they had elected themselves, in their own clothes, with their own rifles. There were no uniforms and no medals. Power tended to concentrate in the wealthier families, who built networks of debt and patronage, and the men most likely to be elected as generals were the takhaars, the long-bearded patriarchs whose age was taken as a sign of wisdom. It was a society one historian likened to the marcher lords of medieval Europe.

By the 1870s a near-bankrupt ZAR found itself caught in Britain's larger ambition to confederate Southern Africa. In 1877, with the republic insolvent and unsettled by war with the Bapedi king Sekhukhune, the British envoy Sir Theophilus Shepstone simply annexed it, claiming the consent of its people. The takeover met little resistance at first. But once the British defeated Sekhukhune and removed the threat that had made their protection seem worthwhile, Boer resentment hardened into revolt. In December 1880 the burghers proclaimed their republic restored, and the First Boer War followed. Boer marksmen defeated the British at Laing's Nek, Ingogo, and decisively at Majuba Hill in February 1881, where the British general fell at the head of his men. Rather than escalate, Prime Minister Gladstone chose peace, and by the conventions of 1881 and 1884 the ZAR regained much of its independence.

In 1886 prospectors struck the vast gold reef of the Witwatersrand, and the impoverished republic was transformed almost overnight. Johannesburg sprang up on the open veld and within a decade swelled to roughly a hundred thousand people, the largest city in Southern Africa, one of the fastest-growing on earth. Gold paid for railways, including the line Kruger drove to Lourenço Marques in Portuguese territory so the republic could reach the sea without crossing British ground. But the same gold drew tens of thousands of foreigners, the uitlanders, and the republic's response revealed its sharp inequalities. Citizenship and the vote were reserved for whites who met strict church and residency tests. Indian and Chinese newcomers faced punitive laws restricting where they could live and what they could own, the early skirmishes of a struggle that would later make a young lawyer named Gandhi famous. For the African majority, the gold economy meant labour, taxation, and exclusion from any rights of citizenship at all.

Tension over the uitlanders' rights, sharpened by imperial appetite for the goldfields, brought war again in 1899. Britain demanded the vote for the republic's foreign nationals; Kruger demanded the withdrawal of British troops massing on his borders, and when refused, declared war. The British occupied the ZAR quickly, but many Boers fought on as guerrillas, and Lord Kitchener answered with a scorched-earth campaign, burning farms and herding civilians into what the army called concentration camps. The conditions there were catastrophic. Crowded tents, poor food, and almost no medical care turned the camps into killing grounds: more than four thousand women and over twenty-two thousand children under sixteen died of disease and starvation, roughly half the Boer child population. Black South Africans, swept into separate and equally lethal camps, died in numbers long left uncounted. These were ordinary families, mothers and children with no part in the fighting, and their deaths remain among the most painful chapters of the war.

On 31 May 1902 the Treaty of Vereeniging ended the war and the republic together. The ZAR became the Transvaal Colony, and in 1910 it was folded into the new Union of South Africa. The story flickered once more in 1914, when Boers nostalgic for the old republic launched the Maritz rebellion at the outbreak of the First World War, briefly allying with Germany in hopes of restoring the ZAR. It failed within months. The Transvaal name lived on as a province until 1994, when democratic South Africa redrew the map and named the gold-bearing heart of the old republic Gauteng, a Sotho word meaning "place of gold." The river-crossing republic is gone, but its goldfields still power a nation, and its memory still divides those who recall it as a lost homeland from those who remember it as a state built on their exclusion.