A civil war in Japan, fought from 1868 to 1870 between forces of the ruling Tokugawa Shogunate, supported by the United States and the French Empire, and those seeking to return political power to the Imperial Court, with support by the British Empire. The Imperial forces quickly established dominance, defeating the supporters of the Shogunate, pushing them north. While the Tokugawa Shogunate was dissolved, many of the Shogunate Daimyo remained opposed to Imperial rule. While the Shogunate was attempting to modernize it's army and navy, the remaining supporters relied on traditional combat methods and failed to halt the Imperial advance. The coalition crumbled October 12, 1868 and fled the the island of Ezo with its remaining navy and French advisors.
The survivors acted quickly to establish the Republic of Ezo, modeled after the United States but with suffrage only for those of the old Samurai class. They reached out to foreign legations present in Hakodate, such as the United States, French, and Russians but only the French and Americans would recognize the Republic. Secretly it was agreed the United States would send arms and equipment to Ezo, an effort that would take months to achieve. During the winter, they fortified their defenses around the southern peninsula of Hakodate, with the new modern-styled fortress of Goryōkaku at the center. The Imperial Army and their British allies gathered to strike down this last bastion of the old tradition.
The Imperial Navy arrived in early March 1869, which included the ironclad CSS Stonewall, renamed Kotetsu, purchased from the CSA, and the Battle of Miyako Bay ensued. Despite a surprise dawn attack by the outmatched Ezo Republic Navy the gatling guns of the Kotetsu overwhelmed the wooden ships and obsolete cannons of the republic fleet sinking three vessels. The Imperial Fleet sustained minimal losses and steamed onwards towards Hakodate.
Four United States ships arrived in Hakodate under Admiral John Sewell, two cargo steamers and two ironclad frigates, the Massachusetts and the Revere as escort. On board these vessels were the usual naval compliment of sailors and marines as well as a sizable delivery of armaments negotiated in a deal between French, US and Ezo delagates months earlier. Twenty-four Armstrong cannons, Two hundred Spencer repeating rifles, five thousand outdated Enfield rifles, with mini-ball, powder, and cartridges. Joining the shipment was a contingent of 'military advisors' drawn from the French and US officer cadre and two companies of Unites States Marines to "safeguard the armaments". The Imperial Fleet was close enough to see the US vessels but were unwilling to engage, not knowing that the armaments on board would change the course of the war.
In response to the US and French involvement two British frigates, the Dorchester and the Enceladus with five hundred British Marines, veterans of the Taiping Rebellion arrived to support the Imperial Fleet mid-November 1869. It had been just 18 months since the end of the Second American War and the British Captain in command of the vessels was eager to get his troops engaged against the United States.
During the Battle of Hakodate, the British deployed Marines in support of the Imperial Forces while a large flotilla of Imperial warships began a merciless bombardment of the Republic defenses. Itching to retaliate for the losses of the British invasion of the USA, and to win the first victory against the British on foreign soil, the US Admiral John Sewell, commanding from the USS Massachussets deployed his US Marine detachment alongside with Ezo soldiers in defending the beachhead. Despite their defensive advantage, the US Marines and Ezo soldiers were outmatched and outflanked by the veteran British Marines. The Federals and Ezo troops hotly engaged the British several times over the course of two days without success and fell back to the fortress to wait out the siege.
The Battle of Hakodate began December 4, 1869 and lasted until March 15, 1870. Using the weapons provided by the United States and tactics of both French and US advisors, the Ezo troops were able to hold back the Imperial forces. The siege was unsuccessful largely due to the inability of the Imperial troops to prevent provisions from reaching the fortress. The final end of the conflict occurred in the winter of 1870 when the harsh weather caused more casualties to the poorly protected Imperial troops and the frozen bay. When the thaw came, several ships were too damaged to move, the Imperial forces were down to less than two thousand combat effective troops, and with rumor of a French fleet arriving to support the Ezo navy the Imperial fleet withdrew to mainland Japan.
To this day the Empire of Japan claims ownership of the island of Hokkaido and denounces the Republic of Ezo as traitors and rebels. The tense stalemate is held in place by the presence of foreign warships on both sides, the kindling of a foreign war waiting for the match.