Treaty of Tientsin
The 1858 Treaty of Tientsin specified Tamsui as an open port. The Port of Keelung opened few years later in 1886. In the Japanese colonial period, the Governor-General of Taiwan started the development of Keelung Harbor. By the early and middle 20th century, it was the largest port in Taiwan at the time. The Port of Keelung brought prosperity to the city of Keelung, with Keelung growing into the 4th largest city in Taiwan (after Taipei, Tainan, Kaohsiung).