Russo-Japanese War: In New Hampshire, United States, the Treaty of Portsmouth, mediated by U.S. President Theodore Roosevelt, ends the war.

The Russo-Japanese War was fought between the Russian Empire and the Empire of Japan over rival imperial ambitions in Manchuria and the Korean Empire. The major land battles of the war were fought on the Liaodong Peninsula and near Mukden in Southern Manchuria, with naval battles taking place in the Yellow Sea and the Sea of Japan.

New Hampshire is a state in the New England region of the Northeastern United States. It borders Massachusetts to the south, Vermont to the west, Maine and the Gulf of Maine to the east, and the Canadian province of Quebec to the north. Of the 50 U.S. states, New Hampshire is the seventh-smallest by land area and the tenth-least populous, with a population of 1,377,529 residents as of the 2020 census. Concord is the state capital and Manchester is the most populous city. New Hampshire's motto, "Live Free or Die", reflects its role in the American Revolutionary War; its nickname, "The Granite State", refers to its extensive granite formations and quarries. It is well known for holding the first primary in the U.S. presidential election cycle, and its resulting influence on American electoral politics.

The Treaty of Portsmouth is a treaty that formally ended the 1904–1905 Russo-Japanese War. It was signed on September 5, 1905, after negotiations from August 6 to 30, at the Portsmouth Naval Shipyard in Kittery, Maine, United States. U.S. President Theodore Roosevelt was instrumental in the negotiations and won the Nobel Peace Prize for his efforts, the first ever American recipient. The treaty recognized Japan's hegemony in Korea, awarded it Russia's lease on the Liaodong Peninsula, control of the Russian-built South Manchuria Railway, and the southern half of the island of Sakhalin (Karafuto).

Theodore Roosevelt Jr., also known as Teddy or T. R., was the 26th president of the United States, serving from 1901 to 1909. Roosevelt previously was involved in New York politics, including serving as the state's 33rd governor for two years. He served as the 25th vice president under President William McKinley for six months in 1901, assuming the presidency after McKinley's assassination. As president, Roosevelt emerged as a leader of the Republican Party and became a driving force for anti-trust and Progressive Era policies.