Cacos insurgents, quasi-military mountain tribes who served as mercenaries for the highest bidder, routinely attacked political targets, as well as ordinary Haitians, to sustain themselves.

The trio of Marines immediately began to fire on the 75 surprised Cacos in the fort—Butler described them as "half naked madmen, howling and leaping"—and they were joined shortly by the rest of the 5th Company streaming through the drain.

Private Gross dispatched a massive Cacos with his rifle just moments before he would have struck a devastating blow to Butler's head with a club.

As panic overtook the Cacos, Butler wrote that they "threw away their loaded guns and grabbed swords and clubs, rocks and bricks, which were no match for bullets and bayonets."

After ten minutes of intense hand-to-hand combat, the Marines had killed some 50 Cacos and taken the remainder prisoner; those who had escaped the fort were cut down or captured by the force covering the south wall.