World War I: Start of the Battle of St. Quentin in which the French Fifth Army counter-attacked the invading Germans at Saint-Quentin, Aisne.

World War I or the First World War, also known as the Great War, was a global conflict between two coalitions: the Allies and the Central Powers. Main areas of conflict included Europe and the Middle East, as well as parts of Africa and the Asia-Pacific. There were important developments in weaponry including tanks, aircraft, artillery, machine guns, and chemical weapons. One of the deadliest conflicts in history, it resulted in an estimated 30 million military casualties, plus another 8 million civilian deaths from war-related causes and genocide. The movement of large numbers of people was a major factor in the deadly Spanish flu pandemic.

The Battle of St. Quentin (also called the First Battle of Guise was fought from 29 to 30 August 1914, during the First World War.

The Fifth Army was a fighting force that participated in World War I.

Saint-Quentin is a city in the Aisne department, Hauts-de-France, northern France. It has been identified as the Augusta Veromanduorum of antiquity. It is named after Saint Quentin of Amiens, who is said to have been martyred there in the 3rd century.