Built in a matter of weeks by soldiers, prison labourers and cadres of the unemployed, a vast new wall along Balkan frontiers is a monument to the ruthless efficiency with which Prime Minister Viktor Orban has mobilised Hungary against migrants. Orban describes the arrival of hundreds of thousands of refugees and other migrants in Europe this year from Asia, Africa and the Middle East as an attack on the continent's Christian welfare model.

While Europe dithered over a collective response, Hungary took matters into its own hands, shutting off the route with a new fence along its entire 175 km (110 mile) border with Serbia, topped with razor wire and guarded by helmeted riot police. In just days since it shut the Serbian frontier, Hungary has already moved even faster to shut the border with Croatia, which is inside the European Union but outside the Schengen zone. A 41-kilometre temporary fence was thrown up within four days. Work is already underway on a permanent barrier, with machines clearing the land, fence posts driven into the ground and razor wire rolled out.

The military initially called in private contractors, but after Orban forced out his defence minister over the slow pace of work, soldiers swiftly took over most of the project. Janos, a dispatcher for a construction firm specialising in earth moving equipment, described a frenzied start. "They found us through the Internet, I just got a call from the military asking if I could do the job," he said, asking that his surname not be used while discussing the process. "They had something like two dozen private companies in the project then. But we're down to maybe a quarter of that as the military is getting its house in order and replaces us with their own capacity."

Parts of the fence have been made by firms using prison labour. Convicts receive a small portion of the wages paid for their work; the rest goes to cover prison costs. Inmates from a prison on the outskirts of Dunaujvaros, Hungary's top steelmaking town, make up about a third of the 500-strong workforce at DAK Acelszerkezeti Kft., which worked on steel fence posts.

The state has also mobilised unemployed people who collect government benefits through a public works programme. "Public works people have an obligation to work, otherwise they could lose their benefits," said Marta Varga, a spokeswoman for the Csongrad county government offices.

In recent weeks Orban has been denouncing European leaders for accelerating Europe's migration crisis by abandoning any pretence of defending its external borders. Orban's speeches and interviews have included warnings that Europe's Christian culture is in jeopardy from Muslim migrants, a tone critics say crosses a line into xenophobia. Orban's opponents abroad say Hungary should be more compassionate, not least because of its own history, including a 1956 uprising against the Soviet Union when Russian guns and tanks drove nearly 200,000 Hungarians to flee.