Huddled in brightly lit yards late one recent night, hundreds of inmates taunted a team of about a dozen special forces who were rounding the walls along the top of Kunduz prison.

The appearance of elite soldiers was an anomaly, a sign to the prisoners that something was happening. “What’s going on?” they shouted. “Is tonight going to be our last night in here?

Taliban fighters planned to storm the compound that evening, according to information gathered by local intelligence officers. Government forces hoped the show of force would spur prisoners — some in possession of smuggled cellphones used to communicate with the Taliban — to wave off the attack.

Without enough fighters to hold the city’s front lines and reinforce the prison, the special forces’ move was a gamble. But it appeared to work: The night passed without incident.