In 1842, Rhenish missionaries Carl Hugo Hahn and Franz Heinrich Kleinschmidt were living in Windhoek when Wesleyan missionaries arrived at the invitation of Jonker Afrikaner, the powerful Oorlam leader. Fearing conflict between the missions, Hahn and Kleinschmidt relocated to Otjikango, where they established the first Rhenish mission station to the Herero people in late 1844. They named it Barmen, after the German city — today part of Wuppertal — where the Rhenish Missionary Society had its headquarters. The ruins of their missionary house are still visible on the site. Hahn tried to teach the Herero Western farming techniques and settle them permanently, but the experiment unraveled when Jonker Afrikaner's Nama warriors began their raids. By 1850, the Herero had fled Otjikango to escape the violence, and Hahn was reassigned.

The Reverend Peter Heinrich Brincker arrived at Gross Barmen in 1864, newly married and determined to resume the ministry. What followed was a pattern of astonishing persistence. Nama attacks forced Brincker to flee the station no fewer than seven times, and seven times he returned. When the station's residents finally abandoned Gross Barmen in 1866, Brincker retreated to Otjimbingwe — only to come back months later when the Eastern Herero, known as the Mbandjeru, unexpectedly settled at the springs. He had some success among them, but they eventually left to join Chief Maharero in Okahandja. Brincker went back to Otjimbingwe again, then returned once more to Gross Barmen in 1869 as the Herero-Nama War wound down. This time he stayed long enough to rebuild properly, constructing a school and a church.

The Peace of Okahandja, signed on 13 September 1870, brought a fragile stability that the missionaries had spent years working to broker. In the decade that followed, Gross Barmen quietly flourished. The station grew to 251 residents, and 130 children attended Brincker's school — numbers that speak to a community putting down roots after years of displacement. After a visit to Germany in February 1880, Brincker returned to South West Africa but chose Otjimbingwe over Gross Barmen this time. The mission station continued operating without him, serving the Herero community through the remaining years of the nineteenth century. It would not survive the next war.

In 1904, the Herero and Nama Genocide began — the German colonial government's brutal campaign against the Herero and Nama peoples. Herero insurgents destroyed the mission station at Gross Barmen, along with the police post that had been established there. The settlement that missionaries had built, abandoned, rebuilt, and defended for sixty years was reduced to ruins in the opening months of a conflict that would claim the lives of tens of thousands of Herero and Nama people. What survived was the water. The hot springs kept flowing, indifferent to the destruction around them. In time, the site was redeveloped as a recreational resort. Namibia Wildlife Resorts undertook a major redevelopment project, and Gross Barmen became what it is today: a place where families from Windhoek come to soak in thermal pools on weekend afternoons. The name lingers from a German city thousands of miles away, attached now to warm water and leisure rather than the cycles of flight and return that defined its first half-century.