This section outlines a number of the more famous and/or controversial cases of
casus belli which have occurred in modern times.
Second Opium War Europeans had access to Chinese ports as outlined in the
Treaty of Nanking from the
First Opium War. France used the execution of
Auguste Chapdelaine as a
casus belli for the
Second Opium War. On February 29, 1856, Chapdelaine, a French missionary, was killed in the province of
Guangxi, which was not open to foreigners. In response, British and French forces quickly took control of
Guangzhou (Canton).
American Civil War While long-term conflict between the
Northern and
Southern States (mainly due to moral questions caused by
slavery, as well as socio-economic disparities) was the cause of the
American Civil War, the
Confederate attack on Fort Sumter (April 12–14, 1861) served as the
casus belli for the
Union.
Spanish–American War placing Spain on notice, c. 1898 The
Maine was a United States Navy ship that sank in
Havana Harbor,
Spanish Cuba on February 15, 1898. While the destruction of the
Maine did not result in an immediate declaration of war with Spain, it did create an atmosphere that precluded a peaceful solution. The Spanish investigation found that the explosion had been caused by spontaneous combustion of the coal bunkers, but the US Sampson Board's Court of Inquiry ruled that the explosion had been caused by an external explosion from a torpedo. The
McKinley administration did not cite the explosion as a
casus belli, but others were already inclined to go to war with Spain over perceived atrocities and loss of control in Cuba. Advocates of war used the rallying cry, "Remember the
Maine! To hell with Spain!"
World War I Austria-Hungary's
casus belli against Serbia in July 1914 was based upon
Serbia's refusal to investigate the involvement of Serbian government officials in the equipping, training and paying the assassins who
murdered Archduke Franz Ferdinand of Austria at
Sarajevo. The Serbian government refused the Austrian Démarche, and Austria-Hungary declared war. For Britain, the direct cause of entering the war was the German invasion and occupation of
Belgium, violating Belgian neutrality which Britain was bound by treaty to uphold. In 1917, the German Empire sent the
Zimmermann Telegram to Mexico, in which they tried to persuade Mexico to join the war and fight against the United States, for which they would be rewarded Texas, New Mexico, and Arizona, all former Mexican territories. This telegram was intercepted by the British, then relayed to the U.S., which led to President
Woodrow Wilson then using it to convince Congress to join World War I alongside the Allies. The Mexican president at the time, Venustiano Carranza, had a military commission assess the feasibility, which concluded that this would not be feasible for a number of reasons.
World War II , who organized and led the
Gleiwitz incident on the orders of
Reinhard Heydrich In
Manchukuo, the
Empire of Japan staged the
Marco Polo Bridge incident in 1937 as a casus belli to initiate the
Second Sino-Japanese War, often considered to be the start of the
Pacific Theatre of the Second World War. In his autobiography
Mein Kampf,
Adolf Hitler had in the 1920s advocated a policy of
Lebensraum ("living space") for the
German people, which in practical terms meant German territorial expansion into Eastern Europe. In August 1939, to implement the first phase of this policy,
Nazi Germany's government under Hitler's leadership staged the
Gleiwitz incident, which was used as a '''' for the
invasion of Poland the following September. Nazi forces used
concentration camp prisoners posing as Poles on 31 August 1939, to attack the German radio station Sender Gleiwitz in Gleiwitz, Upper Silesia, Germany (now
Gliwice, Poland) on the eve of World War II. Poland's allies, the
United Kingdom and
France, subsequently declared war on Germany in accordance with their alliance. The
United States would declare war on
Japan after the
attack on Pearl Harbor on December 7, 1941. In 1941, acting once again in accordance with the policy of Lebensraum, Nazi Germany
invaded the Soviet Union, using the
casus belli of
preemptive war to justify the act of aggression.
Vietnam War Many historians have suggested that the Second
Gulf of Tonkin incident was a manufactured pretext for the
Vietnam War. North Vietnamese Naval officials have publicly stated that during the second incident the was never fired on by North Vietnamese naval forces. In the documentary film
The Fog of War, then-US Defense Secretary
Robert McNamara concedes the attack during the second incident did not happen, though he says that he and President Johnson believed it did so at the time. The first Gulf of Tonkin Incident (2 August) should not be confused with the second Gulf of Tonkin Incident (4 August). The North Vietnamese claimed that on 2 August, US destroyer USS
Maddox was hit by one torpedo and that one of the American aircraft had been shot down in North Vietnamese territorial waters. The PAVN Museum in Hanoi displays "Part of a torpedo boat ... which successfully chased away the USS Maddox August 2nd, 1964". The
casus belli for the Vietnam War was the second incident. On 4 August, USS
Maddox was launched to the North Vietnamese coast to "show the flag" after the first incident. The US authorities claimed that two Vietnamese boats tried to attack USS
Maddox and were sunk. The government of North Vietnam denied the second incident completely.
1967 Arab-Israeli War A
casus belli played a prominent role during the
Six-Day War of 1967. The Israeli government had a short list of '''', acts that it would consider provocations justifying armed retaliation. The most important was a blockade of the
Straits of Tiran leading into
Eilat, Israel's only port to the
Red Sea, through which Israel received much of its oil. After several border incidents between Israel and
Egypt's allies
Syria and
Jordan, Egypt expelled
UNEF peacekeepers from the
Sinai Peninsula, established a military presence at
Sharm el-Sheikh, and announced a blockade of the straits, prompting Israel to cite its
casus belli in opening hostilities against Egypt.
China-Vietnam War During the 1979
Sino-Vietnamese War, China's leader
Deng Xiaoping told the United States that its plan to fight the Vietnamese was revenge for Vietnam's
toppling of the
Khmer Rouge regime of
Cambodia, an ally of China. However Chinese nationalists have argued that the real
casus belli was Vietnam's
poor treatment of its ethnic Chinese population, as well as suspicion of Vietnam trying to consolidate Cambodia with Soviet backing.
2003 United States invasion of Iraq holding a model vial of
anthrax while giving the presentation to the
UN Security Council When the United States
invaded Iraq in 2003, it cited Iraq's non-compliance with the terms of cease-fire agreement for the 1990–1991
Gulf War, as well as planning in the
1993 attempted assassination of former president
George H. W. Bush and firing on coalition aircraft enforcing the
no-fly zones as its stated ''''. Cited by the
George W. Bush administration was
Saddam Hussein's
weapons of mass destruction (WMD) program and his connections to
al-Qaeda after the
September 11 attacks in 2001. The administration claimed that Iraq had not conformed with its obligation to disarm under past UN Resolutions, and that Saddam Hussein was actively attempting to acquire a nuclear weapons capability as well as enhance an existing arsenal of chemical and biological weapons. Secretary of State
Colin Powell addressed a plenary session of the
United Nations Security Council on February 5, 2003, citing these reasons as justification for military action. Since-declassified National Intelligence Estimates (NIE's) indicate that any certainty may have been overstated in justification of armed intervention; the extent, origin and intent of these overstatements cannot be conclusively determined from the NIE.
Russia-Ukraine War Annexation of Crimea After the
annexation of Crimea by the Russian Federation in 2014, Russian President
Vladimir Putin argued that Crimea and other regions "were not part of Ukraine" after it was taken in the 18th century. The ethnic Russian population in Crimea and eastern Ukraine has been seen as a
casus belli for Russia's annexation. The Foreign Ministry claimed that Ukraine tried to seize Crimean government buildings, citing this as a
casus belli.
2022 Russian Invasion of Ukraine Prior to the
2022 Russian invasion of Ukraine, Russia recognized the separatist republics in
Donetsk and
Luhansk, and the alliance between them was ratified in their parliaments, thus creating a usable
casus belli. Russia also claimed a
genocide was being committed against
Russian speakers in
Ukraine by
neo-Nazi groups and that the
Ukrainian government were neo-Nazis. A false-flag operation was also considered by Russia, according to US, UK, and Ukrainian intelligence.
2023 Israel–Gaza war On October 7, 2023,
Palestinian militant groups, led by
Hamas,
launched a major attack into
Israeli territory from the
Gaza Strip. This operation was called 'Operation Al-Aqsa Flood' by Hamas. This was viewed by Israel as
casus belli. In response, the Israel Defense Forces launched a counteroffensive, officially named 'Operation Iron Swords'. == See also ==