Separating causes into categories

Wars rarely result from one cause. Economic, ideological, political and territorial pressures often overlap. Nationalism, ethnic division, religion, security fears or personal leadership may then intensify the conflict.

These categories are tools for analysis, not separate explanations. The same territorial dispute may carry economic value and ideological meaning while also having political importance.

Illustrative wars

The Korean War (1950–1953) developed from the division of Korea at the 38th parallel in 1945. Both Kim Il Sung and Syngman Rhee claimed authority over the whole peninsula. Ideological hostility between communism and anti-communism reinforced this political and territorial conflict, as did the wider Cold War.

The Angolan Civil War (1975–2002) began after the Portuguese withdrawal. The MPLA, UNITA and FNLA fought for control of the new state. The conflict drew on rival political movements and ideological differences, alongside regional and ethnic loyalties and access to oil and diamonds.

The Arab–Israeli War of 1948–1949 centred on competing claims to the former British Mandate of Palestine. Zionism and Arab nationalism provided ideological and national aims. Meanwhile, the end of British rule and the rejection of the United Nations partition plan triggered an immediate political crisis.

These examples are illustrations only. A course may choose other appropriate 20th-century wars, including cases from different IB regions.

The causal chain

Long-term causes develop over an extended period, creating conditions that make conflict increasingly likely. Short-term causes occur close to the outbreak and turn existing tension into an immediate crisis.

A trigger is the event that starts hostilities or sharply accelerates them. It isn’t a complete explanation on its own. The trigger has such an impact because earlier conditions have already made compromise or restraint difficult.

One useful causal sequence is:

1. underlying conditions;
2. growing tensions;
3. decisions made during a crisis;
4. trigger and outbreak.

Illustrative wars

In the Korean War, the long-term causes included Japanese colonial rule, the emergence of rival Korean political movements and the Cold War division imposed after 1945. Border fighting and the consolidation of rival governments in 1948 were short-term causes, as were Kim Il Sung's efforts to gain Soviet and Chinese approval. The trigger was North Korea's invasion on 25 June 1950.

The Six-Day War (1967) grew out of the unresolved Arab–Israeli conflict, Palestinian displacement and repeated border disputes. In the short term, clashes involving Israel and Syria increased tensions. Egyptian troop movements into Sinai, the removal of the United Nations Emergency Force and Egypt's closure of the Straits of Tiran pushed the crisis further. Israel's air strikes on 5 June began the war.

For the Angolan Civil War, the long struggle against Portuguese colonial rule and rivalry among liberation movements created the long-term background. Portugal's 1974 revolution and rapid decolonization then caused a short-term collapse of authority. Fighting among the MPLA, FNLA and UNITA, along with foreign intervention, prevented an agreed transfer of power in 1975.

Relative importance

Long-term conditions show why a society was vulnerable to war, but they don’t prove that conflict was inevitable. Short-term choices shape the timing. They can also reveal the importance of leadership, miscalculation and failed diplomacy.

Types of war

A civil war is an armed struggle within a state. It usually involves organized groups fighting for control of the government, independence or a fundamental change in the political order.

A war between states is fought mainly between the armed forces of sovereign states.

In a guerrilla war, dispersed and mobile forces avoid prolonged conventional battles. Instead, they depend on ambushes, raids, sabotage and support from sections of the population.

The forms may overlap. Foreign armies can become involved in a civil war, while guerrillas may gradually gain the organization and weapons required for conventional operations.

Illustrative wars and outcomes

The Korean War grew out of Korea’s civil and political division, but it developed into a major war between organized forces backed by foreign states. North Korea’s first conventional offensive came close to defeating the South. United Nations intervention reversed the offensive, before Chinese intervention prevented a UN victory over the North. These changes in the character of the war helped create a military stalemate.

The Angolan Civil War involved both conventional campaigns and guerrilla warfare. The MPLA held the state and the major cities. UNITA, drawing on regional bases, carried out mobile operations across a large territory. Political legitimacy or battlefield strength alone couldn’t deliver a rapid victory; outside support and control of resources helped prolong the conflict.

During the Soviet–Afghan War (1979–1989), Soviet and Afghan government forces controlled aircraft, armour and cities. The mujahideen, by contrast, used guerrilla methods in rural and mountainous areas. They didn’t have to defeat every Soviet formation. By surviving, imposing costs and denying secure control, the guerrillas contributed to the Soviet withdrawal.

Technology and military effectiveness

Technology shapes firepower, mobility, communications, intelligence, protection and logistics. How much difference it makes depends on doctrine and training, as well as terrain, maintenance and the coordination of land, naval and air forces. Advanced weapons alone don't guarantee victory.

Land warfare

Tanks and other armoured vehicles gave armies greater mobility and striking power. Artillery still played a major role in suppressing and destroying enemy positions, while helicopters provided transport and fire support across difficult terrain. At the same time, portable anti-tank and anti-aircraft weapons enabled less heavily equipped forces to challenge opponents with stronger technology.

In the Korean War, North Korean tanks helped drive the rapid advances of 1950. UN air power, reinforcements and amphibious operations then contributed to reversing those gains. After the front stabilized, artillery, trenches and fortified positions mattered more than fast armoured movement.

Air warfare

Aircraft could strike military forces, transport networks and economic targets. They also carried out reconnaissance and supported troops on the ground. Air superiority gave forces more freedom of movement, but bombing alone couldn't secure territory or automatically break an opponent's political will.

During the Soviet–Afghan War, Soviet helicopters provided government forces with mobility and firepower. From 1986, foreign-supplied portable surface-to-air missiles made operations more dangerous for Soviet aircraft and restricted some of them. Their impact was significant, though it worked alongside guerrilla resilience, foreign supply networks and Soviet political exhaustion.

Naval warfare

Naval forces defended supply routes, enforced blockades and transported armies. Aircraft carriers also allowed them to project air power. Meanwhile, control over narrow waterways could have both strategic and economic importance.

In the Yom Kippur War (1973), Egyptian forces used anti-tank and surface-to-air missiles around the Suez Canal, reducing Israel's initial technological advantages. Israel later regained the military initiative through adaptation, combined-arms operations and the crossing of the canal. The conflict showed that technology works best when it forms part of a workable operational plan.

What mobilization involves

Mobilization means organizing people and resources for war. Human mobilization covers conscription, recruitment, training and civilian labour, as well as the political effort required to keep people involved. Economic mobilization involves taxation, borrowing, industrial production, food supply, transport and decisions about how to allocate scarce materials.

Mobilization can be judged by its breadth, duration and effectiveness. A government might recruit a large army but still fail to equip, transport or supply it. A smaller force, by contrast, may win if it uses its resources more efficiently or can depend on outside assistance.

Human resources

During the Korean War, both Korean states mobilized large armed forces. United Nations contingents and Chinese forces were also drawn into the conflict. After 1951, replacement troops and the capacity to absorb casualties helped prevent either side from winning a complete victory.

In the Angolan Civil War, the MPLA and UNITA used political organizations and regional networks to recruit fighters. Because the war lasted so long, it placed a heavy burden on civilians. Access to recruits, food, transport and secure territory became central to each side’s military endurance.

Economic resources

War economies channel production and revenue into military needs. Governments may requisition goods, restrict consumption or depend on strategic exports. Economic strength matters only when resources can be turned into usable military power.

Angola shows the difference clearly. Oil provided revenue for the MPLA government, while UNITA financed much of its war through access to diamonds. These resources kept armies in the field and paid for weapons, allowing the conflict to continue even though neither side could secure a stable settlement.

The Second Italo–Ethiopian War (1935–1936) demonstrated the advantage of unequal mobilization. Fascist Italy deployed an industrialized army supplied through Eritrea and Italian Somaliland. Ethiopia mobilized substantial manpower, but it lacked comparable heavy weapons, communications and logistical organization. Italy’s economic and technological capacity contributed to its conventional victory.

Forms of foreign involvement

Foreign powers can shape a war through diplomacy, finance, weapons, training, intelligence, sanctions or propaganda. Direct intervention occurs when a foreign power deploys its own military forces. With Indirect intervention, it supplies or supports a local participant without openly taking control of the fighting.

Such involvement may shift the balance of power, turn a domestic conflict into an international one or block a quick settlement. Sponsors may also limit what local forces can do if they fear escalation.

Illustrative wars

Direct intervention transformed the Korean War. A United States-led United Nations force saved South Korea from collapse before advancing into North Korea. China entered the war in October 1950 and pushed UN forces back. Soviet assistance to North Korea and China was more limited and less openly acknowledged. Foreign intervention secured the survival of both Korean states, contributing to stalemate rather than complete victory.

The Angolan Civil War became entangled in the Cold War. Cuba sent troops to support the MPLA, while the Soviet Union provided military assistance. South Africa intervened against the MPLA. At different stages, the United States supported its opponents. This external backing strengthened local forces, but it also prolonged the war and linked Angolan struggles to broader strategic rivalries.

In the Soviet–Afghan War, the Soviet Union intervened directly in December 1979 to preserve a friendly government. The United States, Pakistan, Saudi Arabia and others gave indirect assistance to mujahideen groups through money, weapons and training. Pakistan's territory played an especially important role as a supply and organizational base. Foreign aid increased the insurgency's ability to keep fighting, though divisions among Afghan groups remained.

Agency and limits

Local actors weren't simply instruments of foreign states. Korean, Angolan and Afghan leaders had political aims of their own; they could pressure, resist or manipulate their sponsors. Foreign involvement interacted with domestic causes rather than replacing them.

Measuring peacemaking

Peacemaking means trying to end armed conflict and secure a political settlement that the parties accept. Methods may include ceasefires, armistices, treaties, mediation, peace conferences or international supervision.

Success comes in degrees. An agreement might halt organized fighting yet leave the original dispute unresolved. A stronger settlement creates accepted political arrangements, includes credible enforcement and withstands later crises.

Illustrative settlements

Large-scale fighting ended with the Korean Armistice of 27 July 1953, which created a Demilitarized Zone near the final front line. It produced a durable cessation of hostilities. However, it neither created a peace treaty nor reunified Korea, and rivalry between the two states continued. The armistice was therefore effective, but the political peace remained incomplete.

The conventional fighting that began in 1948 was ended by the 1949 Arab–Israeli armistice agreements. These agreements established armistice lines between Israel and neighbouring Arab states. They left borders, mutual recognition, Palestinian displacement and the status of Jerusalem unresolved. The renewed wars that followed show the settlement’s limits.

Through power-sharing, consent over constitutional status, cross-border institutions and the involvement of the British and Irish governments, the Good Friday Agreement of 10 April 1998 addressed the conflict in Northern Ireland. It sharply reduced organized political violence and established a political framework, though implementation and disarmament continued to cause disputes.

Why settlements succeed or fail

Peacemaking has a better chance of lasting when the principal parties prefer compromise to further war. Institutions must be able to enforce the agreement, while major external powers need to support it. Excluded groups or ambiguous territorial arrangements can weaken a settlement, as can unresolved grievances and the belief that renewed fighting could bring a better outcome.

Forms of territorial change

War can redraw international borders, split states, create new ones or transfer strategically important areas. In some cases, it leads to occupation without internationally recognized annexation. When assessing territorial outcomes, distinguish between control on the battlefield, the terms of an agreement and long-term recognition.

These changes affect people as well as maps. A new border may divide communities, cause refugee movements or put minorities under a different government.

Illustrative wars

Despite enormous military movement, the Korean War produced remarkably little lasting territorial change. By 1950, Korea was divided near the 38th parallel. The 1953 armistice created a Military Demarcation Line close to this earlier boundary, though the two lines were not identical. Neither side achieved its territorial objective of reunification.

After the Arab–Israeli War of 1948–1949, Israel controlled more territory than the United Nations partition plan had allocated to the proposed Jewish state. Jordan controlled the West Bank and East Jerusalem, while Egypt administered the Gaza Strip. The Palestinian Arab state proposed in the partition plan was not established.

The Six-Day War of 1967 gave Israel major territorial gains. It took the Sinai Peninsula and Gaza Strip from Egypt, the West Bank and East Jerusalem from Jordan, and the Golan Heights from Syria. These territories provided strategic depth and bargaining assets, but they also intensified disputes over occupation, security and Palestinian political rights.

Significance of territorial outcomes

Territorial gains may improve security by creating defensible boundaries. They can also provoke resistance and future wars. Equally, failure to gain territory does not make a war inconsequential: preserving an existing state or preventing an opponent from expanding may itself be a major outcome.

Political effects over time

Short-term political effects emerge during a war or just after it. Governments may collapse, emergency powers can expand, opposition groups may face suppression, and new regimes sometimes take control. Long-term effects include stronger state consolidation, ideological shifts, altered political institutions and lasting international alignments.

Change and continuity can exist in the same outcome. A government might survive while becoming more centralized or militarized, or increasingly dependent on a foreign ally.

Illustrative wars

The Korean War preserved two rival Korean states. In the short term, Kim Il Sung's and Syngman Rhee's governments survived, then intensified repression in the name of national security. North Korea later developed a highly centralized dynastic system. South Korea, meanwhile, remained authoritarian for decades before democratizing in the late 1980s. The war also fixed both states within opposing Cold War alliances.

In Angola, the MPLA retained control of the government after independence in 1975. Wartime conditions strengthened centralized one-party rule and military authority. In the early 1990s, the abandonment of Marxism–Leninism and introduction of multiparty politics changed the formal system, but renewed war blocked stable competition. After UNITA leader Jonas Savimbi's death in 2002, a ceasefire consolidated MPLA dominance.

The Cuban Revolution (1956–1959) overthrew Fulgencio Batista. It immediately created a revolutionary government under Fidel Castro and displaced the old political elite. Power later became concentrated in a one-party communist state closely aligned with the Soviet Union. This transformed Cuba's domestic institutions and its relationship with the United States.

Judging political significance

Durability and depth determine the significance of political consequences. Changing a leader is less extensive than destroying an entire political order. Even so, a leadership change can redirect ideology and alliances while reshaping state institutions.

Economic impact

War can destroy infrastructure and disrupt trade and agriculture. Governments redirect spending towards the conflict, often taking on debt. Yet war may stimulate certain industries, while reconstruction can bring institutional reform. These effects aren't shared evenly: military suppliers may profit as civilians face shortages, inflation or the loss of property.

The Korean War devastated industrial centres, transport networks and settlements across the peninsula. Afterwards, both Korean states needed extensive external assistance. Each followed a different path to reconstruction. Korea's division created separate economic systems and made both states more dependent on rival Cold War blocs.

The Angolan Civil War damaged roads, farms and public services. It also left landmines scattered across productive areas. Oil income allowed the government to keep functioning, but destruction and displacement held back broader development. Economic resources funded the conflict without protecting society from impoverishment.

Social and demographic impact

Demographic impact refers to changes in a population's size, location and composition. War brings military and civilian deaths, injuries and migration. It also causes refugee movements and disrupts family life over the long term.

The 1948 Arab–Israeli conflict created a major Palestinian refugee population. In the following years, Jewish communities also left or were displaced from several Middle Eastern and North African states. These movements changed the social composition of Israel, the Palestinian territories and neighbouring countries. They remained politically significant long after the fighting ended.

Conflict may deepen divisions between ethnic, religious or ideological communities. Displaced people lose access to land and employment, and families are separated. Veterans, widows, orphans and disabled people may then need support from governments already weakened by war.

Women: roles and status

The role of women describes what women do in wartime society. Their status covers their legal rights, political authority, economic position and social standing. Taking on a new role during war doesn't necessarily lead to a lasting improvement in status.

During the Eritrean War of Independence (1961–1991), women worked within the liberation movement as fighters, organizers, medical workers and suppliers. Their participation challenged some established expectations about gender. After independence, though, the greater responsibilities women had carried during the war did not end all legal, economic and social inequalities.

Wartime labour shortages may bring women into agriculture, industry, administration or military service. Once soldiers are demobilized, older employment patterns can return. Whether change lasts depends on political organization and legal reform, as well as whether society continues to recognize women's wartime participation after peace returns.