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Uganda–Tanzania War
The Uganda–Tanzania War, also called the Kagera War or 1979 Liberation War, was an October 1978 to June 1979 conflict in which Idi Amin's Uganda invaded Tanzania and Julius Nyerere's Tanzania counter-invaded, overthrowing Amin in April 1979.
Ugandan Bush War
Ugandan Bush War (1981-1986): civil war between Yoweri Museveni's National Resistance Army and Milton Obote's UPC government, triggered by the disputed December 1980 election, fought mainly in the Luwero Triangle, ending with the NRA taking power in January 1986.
UK undercover policing scandal
The UK undercover policing scandal, also known as the spycops scandal, revealed from 2011 that Met Police undercover units infiltrated political groups, deceiving women into relationships.
Ukraine in the 2026 Iran war
Ukraine in the 2026 Iran war: Ukraine's military, economic, and diplomatic role after the 28 February 2026 US-Israeli strikes on Iran, including interceptor-drone deployments to Jordan, Caspian strikes, aid strain, and the October 2026 rupture with Washington.
Ukrainian attacks on the Russian shadow fleet
Ukrainian attacks on the Russian shadow fleet are drone and special-operations strikes by the SBU against the aging tankers Russia uses to export sanctioned oil and fund its war effort.
Ukrainian collaboration with Nazi Germany
Ukrainian collaboration with Nazi Germany (1941–1944): cooperation of Ukrainian administrations, auxiliary police, Waffen-SS volunteers, and OUN nationalists with German occupiers, including roles in the Holocaust, and its contested historiography.
Ukrainian occupation of Kursk Oblast
The Ukrainian occupation of Kursk Oblast was a 2024–2025 military offensive into Russia. It involved Ukrainian forces and North Korean troops, and marked the first foreign army penetration since WWII.
Ukrainian strikes on Wildberries warehouses
Ukrainian drone campaign begun 17–18 July 2026 against Wildberries, Russia's largest online retailer ("Russia's Amazon"). About 20 sites struck, seven of ten biggest hubs knocked out, over a fifth of warehouse capacity damaged; Ukraine cites military supply role, which the company denies.
Ukrainian War of Independence
The Ukrainian War of Independence (Ukrainian: Vyzvolni zmahannia, "Liberation Struggle"), also called the Ukrainian Revolution, was the 1917–1921 struggle for an independent Ukrainian state, ending in Soviet rule.
Ukrainian–Soviet War
The Ukrainian–Soviet War (українсько-радянська війна) was the intermittent struggle for control of Ukraine from 1917 to 1921, fought between Ukrainian independence forces and pro-Bolshevik forces.
Ulrike Meinhof
Ulrike Marie Meinhof (1934–1976), German journalist and RAF co-founder: konkret editor-in-chief 1960–64, wrote Das Konzept Stadtguerilla, freed Andreas Baader 1970, arrested 1972, died in Stammheim custody 1976.
UN naval blockade of North Korea
The UN naval blockade of North Korea was a maritime interdiction campaign by US and allied naval forces from July 1950 to the 1953 armistice.
Uncle Tom's Cabin
Uncle Tom's Cabin; or, Life Among the Lowly, Harriet Beecher Stowe's 1852 anti-slavery novel, was the 19th century's best-selling US novel and spawned Tom shows, Tomitudes, films, and the contested 'Uncle Tom' epithet.
Unconventional warfare
Unconventional warfare (UW): US doctrine term for enabling a resistance movement or insurgency to coerce, disrupt, or overthrow a government or occupying power through underground, auxiliary, and guerrilla forces; distinct from foreign internal defense and conventional warfare, though the conventional/irregular divide is contested.
Unification of Japan by Toyotomi Hideyoshi
The unification of Japan by Toyotomi Hideyoshi (豊臣秀吉) was the process by which, between 1582 and 1590, Hideyoshi brought all of Japan under one regime, ending the Sengoku wars.
Unification of Saudi Arabia (توحيد المملكة العربية السعودية)
Unification of Saudi Arabia (توحيد المملكة العربية السعودية): Abdulaziz bin Abdulrahman Al Saud's 1902–1932 campaigns from the recapture of Riyadh to the September 23, 1932 royal decree naming the Kingdom of Saudi Arabia.
Union blockade
Union blockade: the US Navy's 1861–1865 closure of Confederate ports proclaimed by Lincoln on April 19, 1861, part of the Anaconda Plan. Over 3,000 miles of coast, 100,000 sailors; porous (runners got through over 90% at Carolina ports) but economically devastating, breaking Confederate transport, food supply, and currency.
Union Street fire
Union Street fire: major Glasgow fire of 8 March 2026 that began in a vape shop and destroyed the B-listed Union Corner Victorian building beside Glasgow Central station, closing Scotland's busiest station; no casualties; cause under investigation.
Unit 731 (731部隊)
Unit 731 (731部隊), the Kwantung Army's Epidemic Prevention and Water Supply Unit under Ishii Shiro, ran biological warfare and human experiments at Pingfang near Harbin, killing thousands; the US later granted immunity for its data.
UNITA
UNITA (União Nacional para a Independência Total de Angola), Angolan movement founded by Jonas Savimbi on 13 March 1966 at Muangai; fought Portugal and then the MPLA in the 1975–2002 civil war; now Angola's main opposition party.
United Airlines Flight 175
United Airlines Flight 175 was a Boeing 767 Boston Logan-to-Los Angeles flight hijacked by five al-Qaeda terrorists on September 11, 2001 and flown into the World Trade Center South Tower at 9:03:11 a.m., killing all aboard.
United Airlines Flight 93
United Airlines Flight 93 was a Boeing 757 flying from Newark to San Francisco, hijacked on September 11, 2001, that crashed in Pennsylvania after passengers fought back.
United Arab Emirates in the 2026 Iran war
United Arab Emirates in the 2026 Iran war: the most-attacked GCC state under Iran's Operation True Promise 4 after the February 28, 2026 US-Israeli strikes, halting trade with Iran, hosting Israeli Iron Dome troops, and exiting OPEC.
United Kingdom and the Russo-Ukrainian war
The UK is a leading supporter of Ukraine in the Russo-Ukrainian war: £25 billion pledged since February 2022, £16 billion military including the £2.26bn ERA loan, Operation Interflex training, over 3,500 sanctions designations, and the 100 Year Partnership.
United Kingdom and the Vietnam War
United Kingdom and the Vietnam War: Britain co-chaired the 1954 Geneva Conference, refused Johnson's troop requests under Harold Wilson, ran the 1966–67 Marigold, Sunflower, and Kosygin Week peace initiatives, and faced Grosvenor Square protests, distinguishing it from Australia and New Zealand, which sent combat troops.
United Kingdom during the Turkish War of Independence
The United Kingdom led the Allied occupation of Ottoman lands during the Turkish War of Independence, faced Turkish forces alone at Chanak in 1922, and signed the 1923 Treaty of Lausanne.
United Kingdom involvement in the 2026 Iran war
United Kingdom involvement in the 2026 Iran war: defensive RAF operations, US use of Diego Garcia and RAF Fairford, the Article 51 legal position, Iranian attacks on UK bases and the September 2026 Fairford plot.
United Nations Command
The United Nations Command (UNC) is the US-led coalition established in 1950 to defend South Korea during the Korean War, and it still enforces the 1953 armistice today.
United Nations General Assembly Resolution ES-11/1
UNGA Resolution ES-11/1, "Aggression against Ukraine", adopted 2 March 2022 at the eleventh emergency special session under Uniting for Peace; passed 141-5-35, demanding Russia cease force and withdraw.
United Nations Partition Plan for Palestine (תוכנית החלוקה)
United Nations Partition Plan for Palestine (תוכנית החלוקה), Resolution 181 (II) of 29 November 1947: proposed Jewish and Arab states with economic union and internationalized Jerusalem; adopted 33-13-10, never implemented.