In 1895, the first year of Japanese occupation, a five-phase construction of Keelung Harbor was initiated, which further stated the importance of Keelung Harbor for the economy and trade of Taiwan.
By 1916, the trade volume of Keelung Harbor has exceeded Danshuei and even Kaohsiung Harbor to become one of the major commercial harbors in Taiwan.
From 1924 to 1931, Keelung became a "City", which makes it the fourth largest city in Taiwan.
Unfortunately, the Pacific War broke out in 1941. As the main commissary and naval harbor, Keelung became the first target of American bombers and the harbor was nearly destroyed by the end of the war.