Nagasaki in the context of "Atomic bombings of Hiroshima and Nagasaki"

Sakoku (Japanese: 鎖国; IPA: [sa̠ko̞kɯ̟]; lit. 'chained country') was the isolationist foreign policy of the Japanese Tokugawa shogunate under which, during the Edo period (from 1603 to 1868), relations and trade between Japan and other countries were severely limited, and almost all foreign nationals were banned from entering Japan, while common Japanese people were kept from leaving the country. The policy was enacted by the shogunate government (bakufu) under Tokugawa Iemitsu through a number of edicts and policies from 1633 to 1639.

Japan was not completely isolated under the sakoku policy. Sakoku was a system in which strict regulations were placed on commerce and foreign relations by the shogunate and certain feudal domains (han). There was extensive trade with China through the port of Nagasaki, in the far west of Japan, with a residential area for the Chinese. The policy stated that the only European influence permitted was the Dutch factory at Dejima in Nagasaki. Western scientific, technical and medical innovations flowed into Japan through Rangaku ("Dutch learning").

The Edo period, also known as the Tokugawa period, is the period between 1600 or 1603 and 1868 in the history of Japan, when the country was under the rule of the Tokugawa shogunate and some 300 regional daimyo, or feudal lords. Emerging from the chaos of the Sengoku period, the Edo period was characterized by prolonged peace and stability, urbanization and economic growth, strict social order, isolationist foreign policies, and popular enjoyment of arts and culture.

In 1600, Tokugawa Ieyasu prevailed at the Battle of Sekigahara and established hegemony over most of Japan, and in 1603 was given the title shogun by Emperor Go-Yōzei. Ieyasu resigned two years later in favor of his son Hidetada, but maintained power, and defeated the primary rival to his authority, Toyotomi Hideyori, at the Siege of Osaka in 1615 before his death the next year. Peace generally prevailed from this point on, making samurai largely redundant. Tokugawa shoguns continued Ieyasu's policies of conformity, including a formalization of social classes in a strict hierarchy. By 1639, all foreigners were expelled under the policy of sakoku, with the exception of Dutch traders on the island of Dejima in Nagasaki, beginning a period of isolation. From 1635, daimyō had to spend alternating years in the capital Edo, where their family was required to reside permanently, in a system of "alternate attendance" in order to keep them in check.

The Black Ships (in Japanese: 黒船, romanized: kurofune, Edo period term) were the names given to both Portuguese merchant ships and American warships arriving in Japan in the 16th and 19th centuries respectively.

In 1543, Portuguese initiated the first contacts, establishing a trade route linking Goa to Nagasaki. The large carracks engaged in this trade had the hull painted black with pitch, and the term came to represent all Western vessels. In 1639, after suppressing a rebellion blamed on the influence of Christian thought, the ruling Tokugawa shogunate retreated into an isolationist policy, the Sakoku. During this "locked state", contact with Japan by Westerners was restricted to Dutch traders on Dejima island at Nagasaki.

The surrender of the Empire of Japan in World War II was announced by Emperor Hirohito on 15 August and formally signed on 2 September 1945, ending the war. By the end of July 1945, the Imperial Japanese Navy (IJN) was incapable of conducting major operations and an Allied invasion of Japan was imminent. Together with the United Kingdom and China, the United States called for the unconditional surrender of Japan in the Potsdam Declaration on 26 July 1945—the alternative being "prompt and utter destruction". While publicly stating their intent to fight on to the bitter end, Japan's leaders (the Supreme Council for the Direction of the War, also known as the "Big Six") were privately making entreaties to the publicly neutral Soviet Union to mediate peace on terms more favorable to the Japanese. While maintaining a sufficient level of diplomatic engagement with the Japanese to give them the impression they might be willing to mediate, the Soviets were covertly preparing to attack Japanese forces in Manchuria and Korea (in addition to South Sakhalin and the Kuril Islands) in fulfillment of promises they had secretly made to the US and the UK at the Tehran and Yalta Conferences.

On 6 August 1945, at 8:15 am local time, the United States detonated an atomic bomb over the Japanese city of Hiroshima. Sixteen hours later, American president Harry S. Truman called again for Japan's surrender, warning them to "expect a rain of ruin from the air, the like of which has never been seen on this earth." Late on 8 August 1945, in accordance with the Yalta agreements, but in violation of the Soviet–Japanese Neutrality Pact, the Soviet Union declared war on Japan, and soon after midnight on 9 August 1945, the Soviet Union invaded the Japanese puppet state of Manchukuo. Hours later, the U.S. dropped a second atomic bomb on the Japanese city of Nagasaki.

Harry S. Truman (May 8, 1884 – December 26, 1972) was the 33rd president of the United States, serving from 1945 to 1953. As the 34th vice president in 1945, he assumed the presidency upon the death of Franklin D. Roosevelt that year. Subsequently, Truman implemented the Marshall Plan in the aftermath of World War II to rebuild the economy of Western Europe, and established both the Truman Doctrine and NATO to contain the expansion of Soviet communism. A member of the Democratic Party, he proposed numerous New Deal coalition liberal domestic reforms, but few were enacted by the conservative coalition that dominated the United States Congress.

Born in Lamar, Missouri, Truman was raised in Independence, Missouri, and during World War I fought in France as a captain in the Field Artillery. Returning home, he opened a haberdashery in Kansas City, Missouri, and was elected as a judge of Jackson County in 1922. Truman was elected to the U.S. Senate for Missouri in 1934. Between 1940 and 1944, he gained national prominence as the chairman of the Truman Committee, which aimed to reduce waste and inefficiency in wartime contracts. Truman was elected vice president in the 1944 presidential election and became president upon Roosevelt's death in April 1945. Only then was he told about the ongoing Manhattan Project and the atomic bomb. Truman authorized the first and only use of nuclear weapons in war against the Japanese cities of Hiroshima and Nagasaki.

Nagasaki Prefecture (長崎県, Nagasaki-ken) is a prefecture of Japan, mainly located on the island of Kyūshū, although it also includes a number of islands off Kyūshū's northwest coast - including Tsushima and Iki. Nagasaki Prefecture has a population of 1,246,481 (1 February 2025) and has a geographic area of 4,130 km (1,594 sq mi). Nagasaki Prefecture borders Saga Prefecture to the northeast.

Nagasaki is the capital and largest city of Nagasaki Prefecture, with other major cities including Sasebo, Isahaya, and Ōmura. Nagasaki Prefecture is located in western Kyūshū with a territory consisting of many mainland peninsulas centered around Ōmura Bay, as well as islands and archipelagos including Tsushima and Iki in the Korea Strait and the Gotō Islands in the East China Sea. Nagasaki Prefecture is known for its century-long trading history with the Europeans and as the sole place of direct trade and exchange between Japan and the outside world during the Sakoku period. Nagasaki Prefecture is home to several of the Hidden Christian Sites in the Nagasaki Region which have been declared a UNESCO World Heritage Site.

Ecclesiastical Nagasaki refers to the period during which the city of Nagasaki was administered by the Jesuits under the nominal authority of the Ōmura clan.

Contrary to some accounts, it was not a Portuguese colony. Portuguese representatives had only commercial and religious privileges under the Padroado.