The Portuguese had first landed in Sri Lanka in 1505, and their ambition from the start was total control. By 1619, they held the kingdoms of Kotte, Sitawaka, and Jaffna. Only Kandy, sheltered in the central highlands, remained under a native king's rule. The Portuguese had tried to take it in 1594, 1603, and 1630, failing each time against the terrain and the tenacity of the Kandyan defenders. In 1635, King Senarath died and the kingdom was divided. His son took the throne as Rajasinghe II, with his cousins Wijayapala and Kumarasinghe governing the Matale and Uva regions. Rajasinghe was no stranger to fighting the Portuguese; he had battled them at Randeniwela alongside his father in 1630. Now he began negotiations with the Dutch, offering them trading rights in exchange for military help against the Portuguese. When Melo learned of these talks, he accelerated his plans to take Kandy before Dutch reinforcements could arrive.

Melo's provocations escalated beyond the elephant dispute. He detained a caravan of 600 men and bulls, challenged the terms of an existing peace accord with Kandy, and stationed troops at Atapitiya near the kingdom's borders as a show of strength. The Sinhalese reinforced their positions with soldiers from Matale and Uva. When Melo finally marched on Kandy, he found the city evacuated. The Sinhalese had pulled out entirely, leaving the Portuguese to sack and burn an empty capital. It was a trap as old as warfare itself. Melo's army turned back toward Colombo, loaded with plunder but exposed on the march. At Gannoruwa, the road home disappeared. Sinhalese woodsmen had felled trees across the Portuguese path, blocking the route to the Mahaweli River. Troops from Matale sealed the road behind them. Every escape route was cut. The Portuguese army, deep in hostile highland forest, was surrounded.

Sharpshooters hidden in the surrounding forest began picking off stragglers on the fringes of the Portuguese column. On the morning of 28 March 1638, the Sinhalese attacked in force. They struck first at the Lascarins, the local conscripts carrying the Portuguese provisions, separating them from the main body of troops. The Lascarins dropped their loads and fled to rejoin the column. Before the Portuguese could reach the high ground at Kiriwat Talawa, the Sinhalese army encircled them and opened fire with heavy guns, including jingals. The forest and the terrain rendered the Portuguese heavy cannons useless. The combined Kandyan force, bolstered by soldiers from Matale and Uva as well as Indian fighters and Moors, pressed the attack from every direction. Casualties mounted rapidly. Melo sent a request for an armistice. Rajasinghe did not respond directly. Instead, he ordered his drummers to announce that any Sinhalese serving with the Portuguese should leave their ranks immediately; those who remained would be killed the next day.

When the fighting ended, only thirty-three Portuguese soldiers remained alive, along with a number of mercenaries. Rajasinghe and Wijayapala ordered their men to spare the survivors. The heads of the fallen Portuguese were piled before the Sinhalese king. A search for Melo's body found nothing, but soldiers recovered his sword and presented it to Rajasinghe. It was the last battle ever fought between the Portuguese and the Sinhalese, and the final military engagement of the Kingdom of Kandy against European forces. The Portuguese were driven from the island by the Dutch soon afterward, though the Dutch alliance that Rajasinghe had cultivated would prove to be its own form of colonial entanglement. Rajasinghe later presented Melo's captured sword to the Dutch Admiral Adam Westerwolt, a gesture of alliance with his new European partners. The Sinhalese celebrated the victory in the poems Konstantinuhatane and Mahahatane, and Gannoruwa entered Sri Lankan memory as the place where a small highland kingdom broke the colonial power that had swallowed the rest of the island.