The two groups were arrayed in a column marching formation with the filibusters in front, ammo and supply pack-horses in the middle, and the natives bringing up the rear.

Walker's two "captains" were to advance into the city and drive the Legitimists from the streets, while the natives were to follow closely behind to provide protection for their rear and flanks.

But the natives, still some distance from the fighting were interdicted by a large body of Legitimists troops, and believing Walker's contingent to be destroyed the Democratic leader retreated from Rivas.

Walker and his men, still held up in a small patch of houses, all the while reaping a heavy toll upon the Legitimist forces with their rifles noticed that they were alone.

Legitimist forces attempted to bring up a small cannon to shell the filibusters out of the homes, but it was disabled in a sally by the mercenaries.