After WWII, “war courts” were 

tribunals and military courts established by the Allied powers to prosecute war crimes, with the most famous being the International Military Tribunal (IMT) at Nurembergfor major Nazi leaders. There were also subsequent U.S. military tribunals at Nuremberg for other Nazi officials and military courts in occupied Germany, Austria, and Italy for lower-level officials, concentration camp staff, and others. Similarly, the International Military Tribunal for the Far East was established to try Japanese war criminals. 

Key war courts and trials

• International Military Tribunal (IMT) at Nuremberg:
  • Prosecuted 22 major Nazi leaders, including Hermann Göring, Wilhelm Keitel, and Joachim von Ribbentrop.
  • Judges were from the United States, Great Britain, France, and the Soviet Union.
  • The tribunal was formed to try crimes against peace, war crimes, and crimes against humanity.
• Subsequent Nuremberg Trials:
  • A series of 12 trials held from 1946 to 1949, conducted by U.S. military tribunals instead of the international one.
  • These trials prosecuted doctors, industrialists, and other members of the Nazi leadership.
• Other Allied Military Courts:
  • Military courts in the American, British, French, and Soviet zones of occupation in Germany and Austria, and in Italy, tried many lower-level officials.
  • These courts dealt with cases involving concentration camp guards, police, and medical personnel.
• International Military Tribunal for the Far East:
  • Established to prosecute major Japanese war criminals. 

Legal basis and charges

• The authority for the trials came from the Moscow Declaration of 1943, which stated the Allies’ intent to bring Axis war criminals to justice.
• The IMT at Nuremberg was founded on the Nuremberg Charter, which outlined the tribunal’s powers and defined crimes, including war crimes, crimes against humanity, and crimes against peace.
• The trials helped establish a new standard of international justice, with the understanding that leaders would be held accountable for their actions. 
• 
  term “war courts” in the context of World War II primarily refers to the 
  post-war Nuremberg and Tokyo Trials. These international tribunals were established by the Allied powers to prosecute high-ranking military and political leaders of Nazi Germany and the Empire of Japan for war crimes, crimes against peace, and crimes against humanity. 
  
  The European Theater: Nuremberg Trials
  The trials in Europe were held in Nuremberg, Germany, a symbolically significant city as the former site of Nazi propaganda rallies. 
  International Military Tribunal (IMT): The first and most famous set of trials (November 1945 – October 1946) tried 22 major Nazi leaders under the London Charter, which defined the crimes for which they were prosecuted. Nineteen were convicted, and twelve were sentenced to death.
  Subsequent Nuremberg Trials: From 1946 to 1949, the United States held twelve additional military tribunals in Nuremberg for lower-level perpetrators, including physicians (the Doctors’ Trial), judges, industrialists, and SS commanders.
  Other European Trials: In addition to the main tribunals, individual Allied powers (Britain, France, the Soviet Union, and the U.S.) held numerous other military courts and domestic trials in their occupation zones and in the countries where the crimes were committed. These included the Belsen trials and various national Polish, French, and Soviet courts that tried thousands of lower-level officials and collaborators. 
  
  The Pacific Theater: Tokyo Trials
  The Allied powers also established an equivalent system in the Far East to prosecute Japanese war criminals. 
  International Military Tribunal for the Far East (IMTFE): Convened in Tokyo in 1946 and lasting until 1948, this tribunal tried 28 high-ranking Japanese military and government officials. Seven defendants were sentenced to death, and the others received prison sentences.
  Other Pacific Trials: Additional trials were held by various Allied nations in locations such as Manila, Shanghai, and Yokohama for other war crimes committed across the Asia-Pacific region. 
  
  Legacy
  These post-WWII war courts were groundbreaking. They established the principle of individual accountability for atrocities committed during wartime and laid the foundation for modern international criminal law, including the Geneva Conventions and the establishment of the permanent International Criminal Court (ICC) in 2002. 

The term “war courts” can refer to the 

Leipzig war crimes trials held in 1921 to prosecute German war criminals from World War I under the Treaty of Versailles. These trials were largely a failure, but are considered a significant early step towards modern international law for prosecuting war crimes. Beyond these trials, “war courts” could also generally describe the various military justice systems used to handle offenses like desertion or misconduct during the war, which could result in harsh penalties like execution. 

Leipzig war crimes trials

• Purpose: To try German officials accused of war crimes during WWI, as stipulated in the Treaty of Versailles.
• Outcome: Only 12 people were tried with mixed results, and the proceedings were widely seen as a failure at the time.
• Legacy: The trials are now seen as a precursor to modern systems for prosecuting international law violations. 

Other “war courts” and military justice

• Domestic military courts: Each nation had its own military justice system to handle crimes committed by its own soldiers. For example, the German military executed many soldiers for desertion during WWII, but only 18 during WWI, notes Wikipedia.
• Field punishment: This was a form of punishment common during the war that could include being tied in a “crucifixion” position for extended periods, according to Wikipedia. 
• 
  “War courts” during and after World War I generally fell into two categories: 
  military courts-martial for internal army discipline and post-war attempts at international war crimes trials. The latter were largely considered a failure at the time but set precedents for future international justice. 
  
  Courts-Martial (During the War)
  All major armies used courts-martial to enforce military law and discipline among their own troops. 
  Purpose and Jurisdiction: These courts had the authority to try a wide range of offenses, from civilian-style crimes like theft to purely military ones like desertion, cowardice, and mutiny.
  Punishments: Sentences ranged from fines and imprisonment to the death penalty. Thousands of soldiers were sentenced to death, though many sentences were commuted. The British Army, for instance, executed 309 of its own soldiers for capital offences during the war.
  Civilian Trials: Under measures like the Defence of the Realm Act (DORA) in Britain or martial law in other countries like Austria-Hungary and Italy, civilians could also be subjected to military courts or special military courts for war-related offenses, often with reduced legal safeguards. 
  
  Post-War War Crimes Trials (After the War)
  The Treaty of Versailles included provisions for the prosecution of German personnel for war crimes, most notably a clause for the public arraignment of former Kaiser Wilhelm II, which never occurred as the Netherlands refused extradition. 
  The Leipzig Trials: The primary result of the treaty’s stipulations was the Leipzig War Crimes Trials held in 1921. The German Supreme Court (Reichsgericht) in Leipzig tried a small number of Germans accused of war crimes, such as the mistreatment of prisoners of war and sinking hospital ships.
  Outcome and Impact:Limited Scope: Only twelve people were tried, resulting in a few convictions and generally light sentences.
  Public Perception: The trials were widely regarded as a failure and a “juridical farce” by the Allied powers due to perceived German partiality and lack of severe punishment.
  Legacy: Despite their immediate failure, the Leipzig Trials are considered an important, albeit flawed, step toward establishing a comprehensive system for the prosecution of international law violations, which heavily influenced the more robust Nuremberg Trials after World War II. 
• 
  The war significantly expanded the scope and severity of military justice systems across all participating nations, transforming them into a crucial tool for maintaining discipline and national control under the immense pressure of 
  total war. The core changes included: 
  
  Expansion of Jurisdiction and Scope
  Civilian Control: Under emergency legislation like the British Defence of the Realm Act or similar martial law declarations, military courts gained jurisdiction over an increasing spectrum of offenses that affected the war effort, involving both military personnel and civilians.
  Wartime Offenses: New laws, such as the U.S. Espionage and Sedition Acts, criminalized activities like anti-draft speech or actions that could impede military operations, leading to thousands of prosecutions in military and civilian courts.
  Maintaining Manpower: To prevent soldiers from escaping the front lines, many countries amended their codes or suspended prison sentences (up to several years), instead returning convicted soldiers to their units or using corporal punishment to conserve fighting power. 
  
  Increased Severity and Use of Deterrence 
  Harsh Discipline: Military justice was often applied with extreme rigor, acting as a primary instrument of coercion and deterrence to force soldiers to continue fighting in brutal trench warfare conditions.
  High Execution Rates: Thousands of soldiers were executed by their own armies for charges such as desertion, cowardice, or mutiny. The Italian army, for example, had one of the highest execution rates, with around 750 soldiers executed by firing squad, compared to approximately 350 in the British army and fewer than fifty in the German army.
  Lack of Oversight: In the early months of the war, the distance between the front lines and national governments allowed military leadership significant latitude in enforcing severe court-martials with little oversight, leading to quick trials and immediate executions. 
  
  Adaptation and Post-War Reflection
  Psychological Trauma: As the war dragged on, courts-martial had to confront cases involving soldiers suffering from the psychological damage of industrialized warfare (shell shock/PTSD). While many officers remained strict, some courts eventually showed greater leniency and a willingness to commute sentences, with some countries seeing higher rates of presidential pardons towards the end of the conflict.
  Post-War Reforms: The harshness of the wartime systems led to significant public and parliamentary criticism after the war. In Germany, the military penal code was revised in 1917 and 1918 to reduce some punishments. In France and Britain, veterans’ campaigns after the war eventually led to reforms of military justice codes to eliminate the most severe practices and, in some cases, grant posthumous pardons to executed soldiers.