Through the fall and winter, the Islamist militant group Boko Haram has seemed nearly unstoppable. It has captured town after town in northeastern Nigeria and laid siege to the fishing hamlet Baga and nearby villages, killing hundreds of people. But over the weekend, the group finally suffered a significant setback. The militants tried to invade Maiduguri, a city of two million in the northeast, as well as two towns in the area, Monguno and Konduga. While Monguno — which is 80 miles north of Maiduguri and houses a military base — fell under Boko Haram control on Sunday, Maiduguri and Konduga held their ground, in no small part because of vigilantes who fought alongside the Nigerian military.

Hundreds of Boko Haram militants descended upon Maiduguri from two directions and were met by the vigilantes and soldiers. The assault prompted Nigerian troops, who were caught by surprise, to call in airstrikes. Scores of Boko Haram members — and probably soldiers too, though numbers have not been released — were killed in the fighting. Without the vigilantes, the battle would have most likely been lost.

One of these vigilantes was Abba Aji Kalli, whom I wrote about for the magazine in November. I called Kalli early this week to find out how he was faring after the battle. “We are doing fine,” he told me. “We pushed them back. They didn’t enter Maiduguri.”

Kalli said his men recovered artillery and rocket-propelled grenades from the militants. None of the vigilantes died in the fight, he added with his usual cockiness, though some were wounded during the battle, which lasted about 90 minutes. “Maiduguri was surrounded by Boko Haram,” Kalli went on. “They had been trying to break into Maiduguri at different locations, but, God help us, we are repelling them.”