Second World War: Allied forces captured San Marino from the German Army.

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 Allies, formally referred to as the United Nations from 1942, were an international military coalition formed during World War II (1939–1945) to oppose the Axis powers. Its principal members were the "Big Four" – the United Kingdom, United States, Soviet Union, and China.

The Battle of San Marino was an engagement on 17–20 September 1944 during the Italian Campaign of the Second World War, in which German Army forces occupied the neutral Republic of San Marino and were then attacked by Allied forces. It is also sometimes known as the Battle of Monte Pulito.

The German Army was the land forces component of the Wehrmacht, the regular armed forces of Nazi Germany, from 1935 until it effectively ceased to exist in 1945 and then was formally dissolved in August 1946. During World War II, a total of about 13.6 million volunteers and conscripts served in the German Army.