On December 30, 1871, Dr. George Leslie Mackay, a Christian priest, arrived in Taiwan at Takao (today's Kaohsiung). Since there were already missionaries in southern Taiwan, including James Laidlaw Maxwell, Dr. Mackay traveled north to Tamsui on March 9, 1872. This date not only not only marks Dr. Mackay's arrival in Tamsui but also serves as the anniversary for the establishment of Tamkang High School.

Before establishing the school, Dr. Mackay conducted his teaching and missionary work in Tamsui through the outdoor "Peripatetic College" or "Itinerant College." In 1880, with support from people in his hometown, he later established the "Oxford College" in Tamsui in 1882, making it the first modern school in Taiwan's history. Meanwhile, Dr. Mackay noticed the low social status of women in Taiwan and founded the Tamsui Girls' School in 1884 to improve the social status of women and recognize their importance in missionary work.