This historic battlefield site is worth the steep 45-minute ascent more for its excellent views than for its historical remains that includes a memorial and an old military building. The mountains, Shimen (石門山) and Wuzhongxi (五重溪山), form a natural entrance here, hence the name, 'Shimen' or 'stone gate'. The battlefield trail is located along County Rd 199 near the 29.5 mark.
Shimen is the site of Mudan Incident (牡丹社事件) in 1871 in which shipwrecked sailors from the then Ryukyu Kingdom accidentally wandered into the autonomous community of Mudan (牡丹社), inhabited by Paiwan tribes. For reasons that vary among Paiwan, Japanese and Chinese versions of the story, dozens of the sailors were killed. This eventually evolved into Japan annexing the Ryukyu Islands. The Ryukyu Kingdom had been paying tribute to China for centuries up untll then. The incident was pivotal in shaping the political landscape in the Asia-Pacific region and Taiwan's fate.