Ponce surrendered to the Americans on July 28, as troops that had marched overland from Yauco were prepared to attack it by land while additional forces were sitting offshore ready to attack by sea. This gave the Americans their first major port on Puerto Rico through which they could funnel troops and supplies, and that led to large-scale troop movements into the interior. One of these was the advance of General Wilson’s 1st Brigade up the Military Road, with the objective of taking several towns in the mountainous interior and then linking-up with General Brooke’s 2nd Brigade at Cayey. The advance met some initial opposition at Coamo, but resistance fell apart quickly as the outflanked and vastly outnumbered Spanish force retreated up the road ahead of the Americans. But the American advance halted about five miles beyond Coamo when cavalry scouts encountered a well-entrenched and strongly-held Spanish position at Aibonito Pass. The Americans bombarded and probed the Spanish lines for several days and sent forces on a flanking maneuver to the north of the Spanish position. The Americans planned a two-pronged attack for August 13th, but it never took place because General Wilson received word that morning of the armistice ending all hostilities with Spain. This scenario depicts the attack that would have taken place at Aibonito Pass that day if the armistice had not yet been signed.

The armistice left Puerto Rico divided, with the Americans in control of the southern half of the island and Spain in control of the north. There were still 8,000 Spanish troops on the island, and had the armistice not been signed the Americans would have had much tough mountain fighting ahead of them on their way to San Juan, followed by a potentially long siege of the capital city. The treaty therefore spared both sides considerable bloodshed.