Ershawan Battery (Tenable Gate of the Sea)

Ershawan Battery (二沙灣砲臺), popularly known as Hǎimén Tiānxiǎn (海門天險, "Tenable Gate of the Sea"), is a historic coastal fortification located on a hilltop overlooking Keelung Harbor in Zhongzheng District, Keelung, Taiwan. It is classified as a National Historic Monument (國定古蹟) and represents over 150 years of Taiwanese military history spanning from the Qing dynasty through the Japanese colonial period.

Origins: The Opium War (1840–1842)

The original battery was constructed in 1840 by Yao Ying (姚瑩), the disciplinary officer (兵備道) of the Qing garrison in Taiwan, as a coastal defense position against the British Royal Navy during the First Opium War. Positioned directly by the sea at Ershawan ("Second Sand Bay"), the battery figured in the Nerbudda affair of September 1841: local officials reported that the British transport Nerbudda fired on the shore, destroying a barracks building, and was driven onto the rocks by return fire, whereas British accounts and a later Qing inquiry held that the ship had been wrecked by weather; in October 1841 HMS Nimrod bombarded the battery.

The Sino-French War (1884–1885)

When the Sino-French War erupted in 1884, Liu Mingchuan (劉銘傳), then in charge of Taiwan's defense, used materials from the original seaside fortification to construct a new battery at the present hilltop location as the centerpiece of his Keelung defense strategy. On 5 August 1884, French warships (three or five, depending on the account) — including the ironclad La Galissonnière — bombarded the Keelung forts, putting Ershawan Battery out of action. During the subsequent Keelung Campaign (October 1884 to April 1885), French forces occupied the battery and renamed it Fort La Galissonnière.

After the French withdrawal in June 1885, Liu Mingchuan — now appointed as Taiwan's first Provincial Governor — undertook a comprehensive reconstruction program. Between 1886 and 1889, a German engineer (recorded in Chinese as 鮑恩士) supervised the construction of the new fortress, which was armed with three Armstrong breech-loading guns (two 6-inch and one 8-inch) purchased from British merchants. The fortress design employed the innovative "mountain-hugging" (靠山砲臺) concept: unlike conventional seaside batteries, Ershawan was built atop coastal hills with barracks positioned on the landward slope, making them virtually impossible to target from the sea.

The Japanese Invasion of Taiwan (1895)

During the Battle of Keelung on 3 June 1895, five Japanese warships bombarded the battery as part of Japan's invasion of Taiwan following the Treaty of Shimonoseki. The Imperial Guards Division captured the fort with little resistance. Under Japanese colonial rule, Ershawan Battery lost its strategic military significance as Japan modernized its coastal defense network with new technology, and the Qing-era fortification gradually fell into disrepair.

Architectural Features

The battery complex occupies an extensive hilltop area and is divided into a northern battery sector and an eastern battery sector. Key surviving structures include:

• A Chinese-style stone city gate (城門) at the southwestern entrance, built with arched stonework and flanked by city walls with battlements and gun ports, inscribed with the characters 海門天險
• Gun emplacements (砲座) with circular platforms and drainage channels
• Ammunition depots (彈藥庫) with thick stone walls
• Barracks foundations (營房) on the protected landward slope
• A freshwater well (水井) that served the garrison
• Defensive walls and slope passages

Legacy and Preservation

On 28 December 1983, the Republic of China's Ministry of the Interior designated Ershawan Battery as a Class One National Historic Monument (一級古蹟), later reclassified as a National Historic Monument (國定古蹟). Today the site is a public park within Zhongzheng Park (中正公園), offering panoramic views of Keelung Harbor. Replica cannons mark the original gun positions, and interpretive signage documents the fort's layered military history. The site also hosts nearby monuments commemorating the 228 Incident and French soldiers killed during the 1884–1885 campaign.