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1860 Treaty of Friendship, Commerce and Navigation signed in Washington DC.
1861-1865 US Civil War, Japanese Navy captures several CSA vessels in the Pacific, no major change from OTL.
April 14, 1865: The Japanese Ambassador and the Lincoln family visit Ford's Theater, John Wilkes Booth mistakes the Ambassador for Lincoln, he shoots the Ambassador and Lincoln is able to bring down Booth. During the fighting, Lincoln stabs Booth in the neck with his pocket knife, killing him. The Japanese ambassador is able to make a full recovery as, in Booth's frenzy he missed his head and instead shot his ear off.
April 22, 1866: The US begins a new Constitutional Convention to rework the government after the devastating Civil War to assure that it will never happen again.
January 3, 1867: The Senate, in the midst of the re-writing of the constitution, accepts the purchase of Alaska.
March 9, 1867: The Constitutional Convention comes to an end and the new constitution is revealed. It destroys the office of the Vice President, abolishes slavery, grants former slaves citizenship, makes citizenship dependent of the parent's citizenship, makes discrimination in government and military illegal, abolishes all sorts of poll test and makes simply being a male citizen the requirement for being a voter. It also makes Christianity the official religion of the United States and re-works the preamble as the National Reform Association recommended it be re-worked. The amendments also re-worked the entire workings of government with the President becoming purely political with the new Colonel-General taking on the duty of the military and foreign affairs. The Senators also now serve at the pleasure the States and Representatives are elected every year. It is otherwise the same.
June 11, 1867: The new Constitution is accepted by the required amount of States and it becomes officially the new Constitution.
July 4, 1867: Abraham Lincoln officially accepts the new Constitution and his new more limited role.
August 19, 1867: Ulysses S. Grant is chosen by Congress to be the first Colonel-General.
October 18, 1867: Alaska becomes United States territory.
New Constitution's Affect
1868 the Boshin War, US Navy and Army assists the Imperial faction and the Shogunate is destroyed.
1870 the Franco-Prussian War occurs as in OTL.
April 3, 1872 the Treaty of Kyoto is signed that divides the world for the settlement of the world. The Japanese are given most of the Pacific and Eastern Asia while the Americans are given the entirety of the Americas, North Pacific and Caribbean.
1872-1898 The Japanese colonize the Pacific, they allow American bases already present in the Pacific and Asia to be continuously occupied. The Japanese overthrow the Hawaiian monarchy and establish their own rule in the nation.