Emkayans and Afghans alike believed they were laying the ground for a prosperous, stable Afghanistan well placed for trade at the heart of Asia.

But the specialists, scientists, planners, economists, and materials were expensive. Salaries and transport costs alone were tremendous. By 1949, the project had already absorbed $20m of the national reserves. Kabul applied for and received loans of $55m from the US Export-Import Bank.

Some observers were uneasy, in the early 1950s, that the project was too big - too ambitious and on a frail financial footing.

“Different factors joined hands to make the project difficult,” says Farouq Azam, an agricultural expert specialising in the Helmand area:

 The government had no experience running such a large project. The Americans didn’t know the area. The investment was not thoroughly examined. The land - the soil - was not surveyed fully.”

The settlers brought in to farm the land, meanwhile, lacked agricultural experience. Unease turned to worry when harvests, rather than increasing, began to fail.

As early as 1954, the water table had risen so much that a large area of land lay waterlogged. An impermeable layer of rock not far beneath the topsoil was preventing proper drainage and meant that salt rose to the surface, leaving fields frosted with white crystals.

In July 1958, Saville R Davis, an American journalist based in Kabul for the Christian Science Monitor, estimated that the Kabul government was pouring one third of the national exchequer into diversion dams and bore holes to drain the land. As an inquiry team flew in from Washington, he wrote:

 The frustrations which assailed this project shouldn’t happen to anyone - but they happened to Afghanistan and the United States. Fine dams were built by an American private contractor working for the Afghan government, but nearly everything seemed to go wrong with the use of the irrigated land.”

The Afghan government, along with American engineers, made tremendous and costly efforts to reverse the early disappointments. In addition to the extra dams, bore holes and channels, scientists developed new seeds and cropping patterns. Educators held classes on new farming techniques.

And despite the setbacks, Helmand began to bloom. Residents and visitors alike remember the bright green of the settlements and orchards along the Helmand river.

Farming increased, harvesting a surplus even at times of drought. Farmers grew and exported cotton for cash in thousands of tonnes. Few even recognised the flower of the opium poppy, according to Farouq Azam.

Glenn Foster finally went home to Watsonville when the MK contract ended in 1959.

Now 38, he settled down and married Lucia, who’d also been out in Afghanistan. He continued to work as an engineer, but film-making as a hobby was prohibitively expensive in those days, so he only made a few home movies of his children, then stopped.

Afghanistan had by now become another country, one increasingly reliant on foreign money. In Washington, and in Geneva, the development industry was emerging.

President John F Kennedy created the United States development agency USAID in 1961 to extend American finance into what was now being called the Third World. It was USAID that took over from Morrison Knudsen in Helmand and, along with the Afghan government, oversaw the next phase of irrigation.

Agriculture, especially cotton and grain production, continued to expand until Helmand supplied a fifth of Afghanistan’s wheat harvest.

USAID commissioned two 16.5 MW generating units in a powerhouse at the foot of the Kajaki dam. Space was left for a third turbine, the “ghost bay”. Electric power began to flow to Kandahar and Lashkar Gah through a series of substations.

Kandahar International Airport was the next big plan. It was a state-of-the-art super-modern complex built in the early 1960s for around $15m in grants and loans. Under its lofty brick arches, Kandahar International was intended to rival Karachi or Delhi as a stopover for planes and passengers travelling between Europe and East Asia.

USAID contracted Morrison Knudsen to do the job, including site engineer Martin Anderson:

 There was to be a huge motel - about 100 rooms. Travellers between, say, Rome and Singapore could stay the night. It was the latest, the latest, technology - six or eight terrific underground fuel tanks with electronic controls, with lines out to the airport aprons. So you could sit in the plane and punch a button, choose which fuel you wanted.”

It was a mystery to Martin how the fuel would arrive in Kandahar. His job was to build. But developments in aircraft technology overtook Kandahar airport before these inventions could come into use.

“When we finished in 1962, the jet engine arrived - planes didn’t need to stop over or refuel,” says Anderson. “You just do what you have to do. The guys took a lot of pride in it. Work like that - it gets in your blood. I don’t know what happened to the motel or the underground fuel tanks. But on the internet I can see the airport now and it looks pretty much as we left it.”