Lieutenant Colonel James Brown of the United States Army stepped off the Black Hawk helicopter straight into a swarm of swinging sticks. "The fight was on," he recalls. "We had to push them back and fight our way to our men." It was April 4, 2000, and Brown was the commanding officer of the Army's 709th Military Police Battalion, part of the United Nations peacekeeping mission in Kosovo. Several hours earlier, a squad of six MPs had searched a house in a mountain-shrouded town called Sevce. They had seized two hand grenades, as well as the grenades' owner. But as the soldiers wrestled their detainee back to their Humvees, a crowd began to gather, a crowd that soon grew to several hundred people, shouting and closing in on the soldiers. There was no way out: The townspeople blocked the streets, and others set up blockades on the edge of town and at a bridge farther down the road.

Brown got a call and raced to the scene with 17 more MPs aboard two Black Hawks. Once on the ground, he and his men, protected by body armor, pushed through the stick-wielding mob. Brown began negotiating with the crowd's leaders. Most crucially, he worked to persuade them that the suspect would be returned. But just as it seemed that they were coming to accept his word, 50 men stormed toward the helicopter that was ready to take the suspect away. They snatched him and began fighting the MPs hand to hand. Several soldiers sustained broken hands or bloodied faces.

Almost immediately, Brown was hit in the neck by a large rock; other rocks pelted members of his team. His men decided that enough was enough. They trained their weapons on the most aggressive attackers and opened fire.

The results were profound—not because of the bloody carnage, but because of the lack of it. Instead of firing hundreds of deadly .223-caliber bullets, the soldiers fired sponge-tipped rounds—40mm-wide canisters capped with green high- density foam, shot from rifle-mounted launchers. One of these hit the man who threw the rock at Brown. He screamed, threw his hands to his face, and bolted in the opposite direction. "The nonlethal rounds achieved a tremendous effect: Everyone backed up immediately and settled down," Brown recalls. "By the rules of engagement, my soldiers could have chosen to shoot people. We would have had a very bloody day, and it would have had a terrible effect on everyone in Kosovo."