General Miles’ invasion plan proceeded with more U.S. Army brigades landing at different cities on the south coast of Puerto Rico. Brigadier General Peter G. Hains landed at Arroyo on August 1st with a brigade consisting of three volunteer infantry regiments plus substantial cavalry and artillery. Included in the latter was a battery of Sims-Dudley dynamite guns. These moved out with two of the volunteer regiments to capture the town of Guayama on the morning of August 5th. Blocking the way were just under a thousand Spanish troops entrenched on the hills near the road.

Superior numbers decided the day, and the Americans pushed the Spaniards off the hill in short order. The latter fled westward to the town of Guayama, but when the Americans sent troops out to probe the town’s defenses they discovered that the Spanish had abandoned it and fled northward. The Americans occupied Guayama and then sent further probes northward the next day, at which point they discovered a strong Spanish force entrenched on the Guamani Heights five miles north of town. It was decided that the Spanish position was too strong to attack, so the advance halted for the time being.