【Introduction】
Following the Sino-French war, which broke out in 1884 (the 10th year of Emperor Guangxu), Liu Mingchuan, the first governor of the Taiwan Province, who arrived in Taiwan as Imperial Inspector Minister on Military Affairs, realized the importance of sea defense for Taiwan and decided to strengthen its coastal defenses by planning to build forts at every major estuary. In 1886, under the supervision of Sun Kaihua, the Provincial military commander, two forts were built in Hobe: “The Key and the Lock to the North Gate," which is the nowadays Hobe Fort, and "The Defense of the East," however, the latter did not survive.
The layout of the Hobe Fort is square-like, layered with the outmost periphery, the trench, the gate, inner walls, the barbettes, the shelters and vaults, corridors, and the central field. The outmost periphery is piled up with soil, which is nearly 10 meters in height. The inner wall of the Fort was built with composite of lime earth concrete; and there are corridors used as space for an ammunition depot and barracks, and are connected with each other providing soldiers with mobility of dispatch.
The base of barbettes is made of cement mixed with gravel for extra durability; these barbettes are gathered up on both sides facing the sea. The biggest one is equipped with a circular rack that has a full 360-degree rotation for cannon shot. The firing angle covers the entire Tamsui River estuary. The arched gate located in the south-east side of the fort still bears the four original Chinese words “Běimén Suǒyuè”, meaning "The Key and the Lock to the North Gate," which are located on the lintel over the door and were inscribed by Liu Mingchuan.