The JapanKorea Treaty of 1876 (also known as the Japan-Korea Treaty of Amity in Japan and the Treaty of Ganghwa Island in Korea) was made between representatives of the Empire of Japan and the Korean Kingdom of Joseon in 1876. Negotiations were concluded on February 26, 1876.In Korea, Heungseon Daewongun, who instituted a policy of closing doors to European powers, was forced into retirement by his son King Gojong and Gojong's wife, Empress Myeongseong. France and the United States had already made several unsuccessful attempts to begin commerce with the Joseon dynasty during the Daewongun's era. However, after he was removed from power, many new officials who supported the idea of opening commerce with foreigners took power. While there was political instability, Japan developed a plan to open and exert influence on Korea before a European power could. In 1875, their plan was put into action: the Un'y, a small Japanese warship, was dispatched to present a show of force and survey coastal waters without Korean permission.

The Empire of Japan was a historical nation-state and great power that existed from the Meiji Restoration in 1868 until the enactment of the post-World War II 1947 constitution and subsequent formation of modern Japan. It encompassed the Japanese archipelago and several colonies, protectorates, mandates, and other territories.

Under the slogans of fukoku kyōhei and shokusan kōgyō, Japan underwent a period of industrialization and militarization, the Meiji Restoration being the fastest modernisation of any country to date, all of these aspects contributed to Japan's emergence as a great power and the establishment of a colonial empire following the First Sino-Japanese War, the Boxer Rebellion, the Russo-Japanese War, and World War I. Economic and political turmoil in the 1920s, including the Great Depression, led to the rise of militarism, nationalism and totalitarianism as embodied in the Showa Statism ideology, eventually culminating in Japan's membership in the Axis alliance and the conquest of a large part of the Asia-Pacific in World War II.Japan's armed forces initially achieved large-scale military successes during the Second Sino-Japanese War (1937–1945) and the Pacific War. However, starting from 1942, particularly after the Battles of Midway and Guadalcanal, Japan was forced to adopt a defensive stance, and the American island hopping campaign meant that Japan was slowly losing all of the territory it had gained, and eventually, the Americans captured Iwo Jima and Okinawa Island, leaving the Japanese mainland completely unprotected. The U.S. forces had planned an invasion, but Japan surrendered following the atomic bombings of Hiroshima and Nagasaki and the nearly simultaneous Soviet declaration of war on August 9, 1945, and subsequent invasion of Manchuria and other territories. The Pacific War officially came to a close on September 2, 1945. A period of occupation by the Allies followed. In 1947, with American involvement, a new constitution was enacted, officially bringing the Empire of Japan to an end, and Japan's Imperial Army was replaced with the Japan Self-Defense Forces. Occupation and reconstruction continued until 1952, eventually forming the current constitutional monarchy known as Japan.

The Empire of Japan had three emperors, although it came to an end partway through Shōwa's reign. The emperors were given posthumous names, and the emperors are as follows: Meiji, Taisho, and Shōwa.