The first signs of armed resistance to the Taliban have come from a narrow valley with a history of repelling invaders.

Just days after the Taliban swept into the capital and toppled the government in a lightning offensive, a group of former mujahedeen fighters and Afghan commandos said they had regrouped and begun a war of resistance in the last area in Afghanistan not under Taliban control.

The man leading them is Ahmad Massoud, the 32-year-old son of the storied mujahedeen commander Ahmad Shah Massoud, stepping into his father’s footsteps 20 years after his death to pick up his dogged fight against the Taliban.