The story of how British troops overcame Taleban resistance to deliver a huge turbine to a remote hydroelectric dam in Afghanistan has a Boy’s Own quality that makes glorious reading (see page 1). This daring operation was one of the largest logistical operations of the seven-year Afghan conflict. It involved 5,000 troops and a classic deception: scoping out one route on the main highway through the valley, while identifying another path through the desert. That such a sensitive load managed to make it safely through more than 100 miles of heavily mined land, under fire, with almost no casualties, is tribute to many individual acts of ingenuity and heroism.

Yet this is also a tale of pragmatism, of the power of electric power. For the past five years the silent Kajaki Dam had become a symbol of resentment at the perceived failure of the international community to make good on its promises to rebuild the country. While it sat idle, and the insurgency intensified, many ordinary people in southern Afghanistan despaired. Now, once the turbine is installed, another is repaired and transmission lines are laid, up to two million people in Helmand and Kandahar provinces will start to receive electricity. The resulting light and heat will make a substantial and visible difference to their daily lives.

Success in Afghanistan will never be achieved by arms alone. Building infrastructure and prosperity is essential if the country is ever to achieve long-term stability. Again and again, insurgents have forced the international effort to focus on security, not the reconstruction that it always intended. But the Kajaki operation brings renewed hope that the tide is turning, and that the allies can offer a demonstrably better life to the people whose territory they occupy.

Sceptics fear that the Taleban will have the last laugh, because they control many of the supply roads and tax the power output. The Taleban will undoubtedly take a cut. But this overlooks the bigger symbolism involved. The operation has proved that allied forces can outwit and overcome the Taleban – killing an estimated 200 insurgents on the way to Kajaki – to mount a complex operation deep in Taleban territory. In the psychological war that is every bit as important as the military battle, Kajaki represents a breakthrough.

This success comes at a vital moment. Although President Sarkozy is steadfast, the French public are wavering in their support after the recent deaths of French soldiers. There is increasing concern within Nato about the grim precedents in Afghanistan for armies that get bogged down there – and a waning appetite for war among Nato citizens. Yet there is too much at stake for governments to lose their nerve. The threat of a failed state is manifest on both sides of the Pakistani border.

The Western allies should take heart from the fact that the Kajaki Dam is a truly international effort: funded by the Americans, built and installed mainly by the Chinese, its supply convoy protected by French, Dutch and Canadian aircraft. This is ambitious reconstruction on the grand scale, which will really improve lives and livelihoods. More such development projects will be needed: but for now, the British Army should congratulate itself on a job well done, and in the best tradition of brilliance, bravery and bluff.