1601–1613), the son of Senapati, was dominated by further warfare, especially against powerful Surabaya, already a major centre of power in East Java. He faced rebellion from his relatives who were installed in the newly conquered Demak (1601–4), Ponorogo (1607–8) and Kediri (1608). In 1612 Surabaya, again, rose against Mataram, as the response Anyokrowati conquered Mojokerto, destroyed Gresik and burned villages around Surabaya. Surabaya however, was still indomitable. The first contact between Mataram and the Dutch East India Company (VOC) occurred under Susuhunan Anyokrowati. Dutch activities at the time were limited to trading from limited coastal settlements, so their interactions with the inland Mataram kingdom were limited, although they did form an alliance against Surabaya in 1613. Susuhunan Anyokrowati died accidentally that year when he was in Krapyak forest, hunting for deer. He was given posthumous title Panembahan Seda ing Krapyak (His Majesty who Died in Krapyak). Golden age Susuhunan Anyokrowati was succeeded by his son, Adipati Martapura. Adipati Martapura, however, was of poor health and quickly replaced by his brother, Raden Mas Rangsang in 1613, who assumed the title Panembahan ing Alaga, and later in 1641 took the title of Sultan Agung Anyokrokusumo ("Great Sultan"). The Mataram Sultanate under the reign of Sultan Agung is popularly remembered as the apogee of Mataram's rule on Java, and the golden age of native Javanese power prior to European colonisation in the following century. Surabaya campaign and eastern conquests Panembahan ing Alaga was an able military general and also a warlike ambitious leader, and he aspired to unite Java under Mataram's banner. He responsible for the great expansion and lasting historical legacy of Mataram due to the extensive military conquests of his long reign from 1613 to 1646. Under Sultan Agung, Mataram was able to expand its territory to include most of Java after capturing several port cities of northern Java. Surabaya with its strong fortification and surrounded by swamps, was still the most formidable enemy of Mataram. In 1614, Surabaya forged an alliance with Kediri, Tuban and Pasuruan, and launched invasion against Mataram. In the following year, Sultan Agung managed to repel allied Surabaya forces in Wirasaba (present day Mojoagung, near Mojokerto). He also conquered Malang, south of Surabaya. In 1616, Surabaya tried to attack Mataram but this army was crushed by Sultan Agung's forces in Siwalan, Pajang (near Solo). The coastal city of Lasem, near Rembang, was conquered in 1616