World War II: Japanese forces land on Java, the main island of the Dutch East Indies, at Merak and Banten Bay (Banten), Eretan Wetan (Indramayu) and Kragan (Rembang).

The Dutch East Indies, also known as the Netherlands East-Indies (Dutch: Nederlands(ch)-Indi; Indonesian: Hindia Belanda) were a Dutch colony consisting of what is now Indonesia. It was formed from the nationalised trading posts of the Dutch East India Company, which came under the administration of the Dutch government in 1800.

During the 19th century, the Dutch possessions and hegemony expanded, reaching the greatest territorial extent in the early 20th century. The Dutch East Indies was one of the most valuable colonies under European rule, and contributed to Dutch global prominence in spice and cash crop trade in the 19th to early 20th centuries. The colonial social order was based on rigid racial and social structures with a Dutch elite living separate from but linked to their native subjects. The term Indonesia came into use for the geographical location after 1880. In the early 20th century, local intellectuals began developing the concept of Indonesia as a nation state, and set the stage for an independence movement.Japan's World War II occupation dismantled much of the Dutch colonial state and economy. Following the Japanese surrender in August 1945, Indonesian nationalists declared independence which they fought to secure during the subsequent Indonesian National Revolution. The Netherlands formally recognised Indonesian sovereignty at the 1949 DutchIndonesian Round Table Conference with the exception of the Netherlands New Guinea (Western New Guinea), which was ceded to Indonesia 14 years later in 1963 under the provisions of the New York Agreement.

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.