VOC forces landed on 4–5 May on Trunajaya's right flank.
Trunajaya did not expect an attack on this flank, and consequently it was only lightly defended.
VOC took Ampel after little resistance.
In the following days, the VOC established its battery in Ampel, simultaneously conducting desultory negotiations with Trunajaya.
Trunajaya accused Speelman of being unknightly by attacking his right flank instead of his main position.
Both Trunajaya and VOC moved their works forward until their artillery batteries faced each other at pistol-shot distance.
Trunajaya dammed the river, the VOC's source of fresh water; afterwards, the VOC troops were limited to brackish water, and diseases soon spread.

At this point, time appeared to be on Trunajaya's side, as further delay would allow him to strengthen his fortifications and reinforcements, while disease would weaken the VOC's forces.
Therefore, Speelman decided to attack.
On 12–13 May, the VOC delivered a heavy artillery bombardment on Trunajaya's main works, followed by an assault.
The attack succeeded after hard fighting, and Trunajaya retreated inland to establish his new capital at Kediri, capital city of the ancient Kediri Kingdom.
In the retreat, he left behind sixty-nine iron cannons and thirty-four bronze cannons (twenty of them small ships' cannons, bassen) and only saved twenty bronze pieces.
VOC forces landed on 4–5 May on Trunajaya's right flank. Trunajaya did not expect an attack on this flank, and consequently it was only lightly defended. VOC took Ampel after little resistance. In the following days, the VOC established its battery in Ampel, simultaneously conducting desultory negotiations with Trunajaya. Trunajaya accused Speelman of being unknightly by attacking his right flank instead of his main position. Both Trunajaya and VOC moved their works forward until their artillery batteries faced each other at pistol-shot distance. Trunajaya dammed the river, the VOC's source of fresh water; afterwards, the VOC troops were limited to brackish water, and diseases soon spread.
At this point, time appeared to be on Trunajaya's side, as further delay would allow him to strengthen his fortifications and reinforcements, while disease would weaken the VOC's forces. Therefore, Speelman decided to attack. On 12–13 May, the VOC delivered a heavy artillery bombardment on Trunajaya's main works, followed by an assault. The attack succeeded after hard fighting, and Trunajaya retreated inland to establish his new capital at Kediri, capital city of the ancient Kediri Kingdom. In the retreat, he left behind sixty-nine iron cannons and thirty-four bronze cannons (twenty of them small ships' cannons, bassen) and only saved twenty bronze pieces.
Battle of Surabaya (1677)