11.5 Conferences and Treaties

Setting the Diplomatic Stage in World War II

World War II was not only fought on battlefields. It was also shaped in meeting rooms, train carriages, and conference halls where leaders negotiated how to fight the war and how to build the peace. The major wartime conferences and the treaties that followed did not just end a conflict, they redrew borders, created new institutions, and set the stage for the Cold War.

This chapter focuses on the most important conferences and treaties of the World War II period, what was decided at them, and why they mattered.

The Atlantic Charter

In August 1941, before the United States had officially entered the war, British Prime Minister Winston Churchill and American President Franklin D. Roosevelt met secretly off the coast of Newfoundland on the warship HMS Prince of Wales. Out of their talks came a short but influential statement called the Atlantic Charter.

The Atlantic Charter was not a formal treaty. It was a joint declaration of principles that described the kind of world the two leaders hoped to build after the defeat of Nazi Germany. It spoke of no territorial expansion, the right of peoples to choose their own form of government, freer trade, disarmament of aggressive nations, and a wider and permanent system of general security.

Many people later saw the Charter as a moral blueprint for the postwar order. Colonized peoples in Asia and Africa took particular note of the promise of self determination, even though Churchill did not intend it to apply fully to the British Empire. The Atlantic Charter also became a basis for later Allied cooperation and for the founding ideas of the United Nations.

The Declaration by United Nations

On 1 January 1942, representatives of 26 countries met in Washington, D.C., and signed the Declaration by United Nations. They endorsed the ideas of the Atlantic Charter and pledged to use all their resources to fight the Axis powers, and not to make a separate peace.

This declaration did not create a new world organization yet, but it did create a formal coalition. For the first time, the term “United Nations” referred to the Allied powers fighting together. The agreement coordinated their war efforts and committed them to a joint victory. More states joined later, making it a broad anti Axis front.

The Declaration by United Nations was important because it tied the military alliance directly to shared political principles and because it provided the name and basic idea for the later UN organization founded in 1945.

The Moscow and Tehran Conferences

As the war dragged on and the front lines shifted, the main Allied powers needed to resolve military and political questions that could not be handled only through letters and intermediaries. Two key conferences in 1943 were central to this effort, one in Moscow and one in Tehran.

In October 1943, the foreign ministers of the United States, Britain, and the Soviet Union met in Moscow. They agreed in the Moscow Declarations that there should be an international organization for peace and security after the war. They also pledged to punish war criminals and reaffirmed that they would fight until the unconditional surrender of Germany and its allies. The Moscow meeting was a step toward the later UN and an early sign that the Allies thought seriously about the postwar order before the war ended.

In November and December 1943, Roosevelt, Churchill, and Soviet leader Joseph Stalin met in Tehran, Iran. The main military issue was the long promised invasion of Western Europe. Stalin pressed for a “second front” to relieve pressure on the Soviet Union. Roosevelt and Churchill confirmed that they would launch a major invasion of northern France in 1944, which later became the D Day landings.

Tehran also touched on political questions, such as the future borders of Poland and the treatment of Germany. Stalin pushed for territorial gains in eastern Poland and for a westward shift of Poland’s borders. Although not all details were fixed, the leaders accepted in principle that Poland would be compensated in the west at Germany’s expense. These discussions foreshadowed how Central and Eastern Europe would look after the war.

The Yalta Conference

In February 1945, when Nazi Germany was close to defeat, Roosevelt, Churchill, and Stalin met again, this time at Yalta, a resort city in Crimea. Yalta was perhaps the most influential wartime conference because it dealt directly with the transition from war to peace.

The first major issue was Germany. The leaders agreed that Germany would be divided into zones of occupation, controlled by the United States, Britain, the Soviet Union, and later France. Berlin, located deep in the Soviet zone, would also be divided into four sectors. They decided that Germany must be disarmed, demilitarized, and forced to pay reparations, although the exact forms of payment were not yet fully defined.

The second issue was the creation of a new international organization to replace the failed League of Nations. At Yalta, the three powers agreed on plans for the United Nations, including a Security Council with permanent members and special voting rights called the veto. The basic structure of the UN was shaped here, although details were completed at a later conference.

The third issue was Eastern Europe, especially Poland. Yalta confirmed that the Soviet backed government in Poland would be enlarged to include some non communist politicians and that free elections would be held. It also accepted the shift of Poland’s borders westward. In practice, the Soviet Union later kept tight control over Poland and other countries it liberated, so the promise of free elections became one of the early points of tension between the Western powers and Moscow.

The leaders also made agreements about the war in Asia. Stalin promised that the Soviet Union would enter the war against Japan within three months after Germany’s defeat, in exchange for certain territorial concessions in Asia, including rights in Manchuria and control over southern Sakhalin and the Kuril Islands.

Yalta has been heavily debated. Some argue that Western leaders conceded too much to Stalin and allowed Soviet dominance over Eastern Europe. Others point out that the Red Army already occupied much of the region, so Western negotiating power was limited. What is clear is that Yalta’s decisions shaped the map of Europe and the framework of the international system for decades.

The Potsdam Conference

By the time of the Potsdam Conference in July and August 1945, the situation had changed dramatically. Germany had surrendered, Roosevelt had died and been replaced by President Harry S. Truman, Churchill was replaced mid conference by Clement Attlee after an election in Britain, and Stalin’s Soviet Union now occupied most of Eastern Europe. The conference took place near Berlin in the suburb of Potsdam, with very different dynamics from Yalta.

At Potsdam, the three leaders focused on how to administer defeated Germany and to settle issues that Yalta had left vague. They agreed on the basic policies for Germany often summarized as the “four Ds”: demilitarization, denazification, democratization, and decentralization. They confirmed the division into occupation zones and outlined how the Allied Control Council would coordinate among the four powers.

The conference also confirmed that Germany would lose significant territory. The eastern German lands east of the Oder and Neisse rivers were placed under the administration of Poland and the Soviet Union, pending a final peace settlement. Millions of Germans were expelled from these areas, a process that took place with much hardship and violence.

The Potsdam leaders also issued the Potsdam Declaration, directed at Japan. It called for Japan’s unconditional surrender and warned of “prompt and utter destruction” if Japan refused. The declaration promised that Japan would be occupied, that its war making power would be removed, but that the Japanese people would not be enslaved or destroyed and could establish a peaceful government. The exact future of the emperor was left ambiguous, which later allowed the United States to keep Emperor Hirohito on the throne under a new constitution.

During the conference, Truman informed Stalin that the United States had successfully tested a new and powerful weapon, the atomic bomb. Stalin already knew from his intelligence services. The presence of this new weapon, together with diverging political aims in Europe, meant that Potsdam was not only the last wartime conference but also an early step into the Cold War era.

The San Francisco Conference and the UN Charter

While the war against Germany was ending, the Allies moved ahead with plans for the new international organization which they had first envisioned in Moscow and later refined at Yalta. In April 1945, delegates from 50 countries met in San Francisco to draft and sign the Charter of the United Nations.

They discussed the balance between the rights of big powers and smaller states, the structure of the main organs of the UN, and the powers of the Security Council. The result was the UN Charter, signed on 26 June 1945. It came into force later that year, after ratification.

The Charter committed member states to prevent war, respect human rights, and promote social and economic progress. It formalized the principle of collective security, where an attack on one member could be treated as a threat to all. The Security Council, with five permanent members the United States, the Soviet Union, Britain, France, and China received primary responsibility for maintaining peace. Each permanent member received a veto over substantive decisions, a direct reflection of the power realities at the end of the war.

The San Francisco Conference turned the diplomatic ideas of earlier meetings into a legal foundation for the postwar order. The UN was not a treaty between victors and the defeated, but an institution meant to prevent future global conflict.

The Treaties Ending the War in Europe

In Europe, World War II formally ended through the capitulation of the Axis powers and later peace arrangements, rather than a single grand treaty like the Treaty of Versailles after World War I.

Germany surrendered unconditionally in May 1945. The main act was the German Instrument of Surrender signed in Reims and then ratified in Berlin. This document ended German military resistance and placed the country under Allied authority. Because the Allies chose to govern Germany directly through occupation rather than immediately negotiate a peace, there was no comprehensive peace treaty with a unified German state at that time.

Italy, which had already switched sides in 1943 after Mussolini’s fall, signed an Armistice in 1943 and then a formal peace treaty in 1947. The Treaty of Peace with Italy, signed in Paris, reduced Italian territory, limited its armed forces, and required reparations to several countries. It also stripped Italy of its colonies in Africa and its possessions in the Balkans.

Other former Axis states in Europe, such as Hungary, Romania, Bulgaria, and Finland, also signed peace treaties in 1947. These treaties adjusted borders, imposed reparations, and set political conditions. They also confirmed the new influence of the Soviet Union in Eastern and Central Europe, since Moscow played a dominant role in shaping the terms for its neighbors.

These postwar European treaties were more modest and dispersed than the settlements after World War I. The Allies hoped to avoid some of the destabilizing effects of the harsh terms imposed on Germany in 1919, but at the same time they accepted large territorial shifts and political changes that reflected wartime realities and Soviet military presence.

The Japanese Surrender and the End of the Pacific War

In Asia and the Pacific, the war ended in a way that was both sudden and shaped by previous diplomatic declarations. After the Potsdam Declaration, Japan initially chose to fight on, even as the situation became desperate. In August 1945, the United States dropped atomic bombs on Hiroshima and Nagasaki, and the Soviet Union declared war on Japan and invaded Japanese held territories in Manchuria.

Faced with these shocks, the Japanese government decided to accept the terms of the Potsdam Declaration, on the condition that the position of the emperor be preserved. The Allies eventually accepted an arrangement that allowed the emperor to remain as a symbolic figure, under Allied authority.

On 2 September 1945, representatives of Japan signed the Instrument of Surrender aboard the American battleship USS Missouri in Tokyo Bay. This short document formally ended hostilities. It placed full authority of the Japanese state in the hands of the Supreme Commander for the Allied Powers, General Douglas MacArthur. It required Japan to carry out the terms of the Potsdam Declaration and to obey any orders issued by the Allied commanders.

The Japanese surrender instrument and the occupation that followed were not a final peace in themselves. That came later with a separate treaty.

The Treaty of San Francisco and the Peace with Japan

The peace settlement with Japan took shape several years after the war ended. The occupation authorities first focused on demilitarization, democratization, and economic change inside Japan. Political tensions between the Western powers and the Soviet Union delayed a comprehensive treaty.

In 1951, delegates from 48 nations gathered in San Francisco to negotiate and sign the Treaty of Peace with Japan, commonly called the Treaty of San Francisco. The Soviet Union, China, and some other states did not sign. The treaty officially ended the state of war, restored Japanese sovereignty, and settled various territorial and reparations issues.

Japan renounced claims to Korea, Taiwan, the Kuril Islands, South Sakhalin, and its former mandates in the Pacific. The treaty did not fully settle who owned some of these territories, which later contributed to regional disputes. The treaty also limited Japan’s ability to maintain large armed forces, although this later changed through reinterpretation. The same conference framework allowed the United States and Japan to sign a separate security treaty that permitted American bases in Japan and tied the two countries together strategically.

The Treaty of San Francisco shows how World War II concluded not with a single global treaty but with a series of regional and bilateral agreements that reflected the emerging Cold War divisions.

War Crimes and the Legal Aftermath

While not traditional peace treaties, the legal actions taken against leaders of the defeated Axis powers were another important diplomatic outcome. The Allies had already promised in the Moscow Declarations that they would punish those responsible for atrocities.

In 1945, the four main victorious powers agreed in the London Charter to create an International Military Tribunal for major war criminals. The most famous result was the Nuremberg Trials, where top Nazi officials were prosecuted for crimes against peace, war crimes, and crimes against humanity. In Asia, a similar tribunal was set up in Tokyo to try Japanese leaders.

These tribunals did not end the war or redraw borders, but they created a precedent for international criminal responsibility. They claimed that individual leaders could be held accountable for starting aggressive wars and for systematic crimes against civilians and prisoners.

The war crimes trials, together with the later adoption of conventions on genocide and human rights, formed part of the wider treaty based effort to prevent a repeat of the brutality seen in World War II.

From Wartime Conferences to Postwar Order

The conferences and treaties of the World War II era were closely interconnected. Early statements like the Atlantic Charter set broad goals. Midwar conferences such as Tehran and Yalta combined military strategy with political planning. Later meetings like Potsdam and San Francisco translated these ideas into concrete occupation policies and lasting institutions.

Two themes run through these diplomatic efforts. The first is the attempt to avoid the mistakes that many believed had been made after World War I, such as isolated peace treaties, lack of enforcement, and the weakness of the League of Nations. The second is the growing tension between the Western Allies and the Soviet Union, which influenced conference outcomes and shaped the postwar treaties.

The resulting system, centered on the United Nations and balanced by rival blocs in Europe and Asia, grew directly out of the negotiations, declarations, and agreements of the World War II years. Understanding these conferences and treaties helps explain why the world after 1945 looked so different from the world before 1939, even though many of the same powers remained on the global stage.