William Jacob Coater who succeeded in completely conjuring Galle fort by 16th March, 1640 AD continued in the Dutch Governorship of Galle until 04th July, 1640 AD. Few months later he is said to have been killed by Natives on his return from a visit to Kandyan king.
Captain Lorenzo Perera De Brito was the Portuguese Commander of Galle fort. On receipt of the news of the surrender of Galle fort Portuguese General Antonio Mascarrannes sent a large force of solders from Colombo to Galle. That armed force had 12 Companies and contained Lascarines, Moorish and Kaffirs.
Forces in fort consisted of 800 Portuguese Kasadoes, 30 groups of trained solders and 30 Lascarines. Despite the maximum possible efforts exerted by Portuguese to protect Galle fort, following a severe war, Dutch acquired Galle fort. Describing this incident in full detail, the Portuguese Historian Quairos explains the war between two parties and assesses the damages caused as well.
Although Dutch succeeded in conquering Galle fort the failed to succeed in maintaining the governance of the fort evenly. As a result of Captain Volrevan De St. Armount who was temporarily assigned as successor to Captain Coster after his death having joined with Portuguese with a group of warriors, security of Galle fort got baffled.
Despite the Dutch stood guard inside Galle fort, Portuguese refused to leave the area surrounding Galle. They completely demolished and destroyed the town outside fort and blocked the routes that supplied food to the fort. Dutch insde the fort were faced with enormous calamities . A large crowd among those in the fort died of Diarrhea, Berry Berry and some other deceases. After conquering Jaffna in 1658 AD only Dutch were able to destroy Portuguese power in coastal areas. So far, protecting the strong Portuguese war base Galle had not been an easy task. During that time Portuguese launched several attacks to grab back Galle from Dutch ND THE Dutch had to exert a great effort protect Galle fort. Dutch ruling powers in Ceylon centering Galle continued from 1640 AD up to 1656 AD under four Dutch Governors. Concurretnt with freeing Colombo fort , main center of governance established in Galle and Galle fort was continued further as the center of governance for Galle area.
By 1662 AD Dutch governors had moved on to develop the peninsula as a fortress town extending approximately to 82 Acres. At that time part of the rampart from Kalu Kotuwa to Ealus tower had been constructed by Portuguese.
Even then, under the leadership of Dutch Commander Adrian Fun Ruthas , certain sections of the rampart were developed . Particularly the restructuring of the rampart from where the warehouse was built up to “Sun” tower and additions of various improvements to main three watch towers were carried out under his guidance. Those sections thus completed had been opened by firing canoes by his wife Maria Ruthas in 1667 AD.