In the mid-nineteenth century, after being forced to engage with Western states, Japan began using punitive expeditions to engage its neighbors - notably Taiwan and Korea. Informing this new approach was the precedent set by Western powers who for a generation utilized ‘gunboat diplomacy’ to achieve trade advantages in East Asia at the expense of weaker states. Traditional historiography has pointed to the U.S. intervention in Japan in the early 1850s as the genesis in Japan’s shift to acquire colonies. However, the 1867 American Taiwan Expedition served a more formulative role because the same international legal right to protect merchants invoked by the Americans was employed by the Japanese in 1874 to justify their intervention. A similar adaptation applies to the U.S. expedition against Korea in 1871, and Japanese intervention there in 1875 - resulting in the 1876 Ganghwa Treaty, which explicitly (Art. VIII) addressed the right to protect merchants. In sum, the use of the anachronist term ‘gunboat diplomacy’ has obscured Japan’s role in being the first East Asian state to adopt Western military-legal conventions.