World War II: The Guadalcanal campaign: American forces defeat an attack by Imperial Japanese Army soldiers in the Battle of the Tenaru.

World War II or the Second World War was a global conflict between two coalitions: the Allies and the Axis powers. Nearly all of the world's countries participated, with many nations mobilising all resources in pursuit of total war. Tanks and aircraft played major roles, enabling the strategic bombing of cities and delivery of the first and only nuclear weapons ever used in war. World War II is the deadliest conflict in history, causing the death of 70 to 85 million people, more than half of whom were civilians. Millions died in genocides, including the Holocaust, and by massacres, starvation, and disease. After the Allied victory, Germany, Austria, Japan, and Korea were occupied, and German and Japanese leaders were tried for war crimes.

The Guadalcanal campaign, also known as the Battle of Guadalcanal and codenamed Operation Watchtower by the United States, was an Allied offensive against forces of the Empire of Japan in the Solomon Islands during the Pacific Theater of World War II. It was fought between 7 August 1942 and 9 February 1943, and involved major land and naval battles on and surrounding the island of Guadalcanal. It was the first major Allied land offensive against Japan during the war.

The Imperial Japanese Army was the principal ground force of the Empire of Japan from 1871 to 1945. It played a central role in Japan’s rapid modernization during the Meiji period, fought in numerous conflicts including the First Sino-Japanese War, the Russo-Japanese War, World War I, the Second Sino-Japanese War, and World War II, and became a dominant force in Japanese politics. Initially formed from domain armies after the Meiji Restoration, it evolved into a powerful modern military influenced by French and German models. The IJA was responsible for several overseas military campaigns, including the invasion of Manchuria, involvement in the Boxer Rebellion, and fighting across the Asia-Pacific during the Pacific War. Notorious for committing widespread war crimes, the army was dissolved after Japan's surrender in 1945, and its functions were succeeded by the Japan Ground Self-Defense Force.