World War I: An Imperial German Navy U-boat opened fire on a small convoy of barges and defending aircraft near the American town of Orleans, Massachusetts.

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.

U-boats are naval submarines operated by Germany, including during the First and Second World Wars. The term is an anglicized form of the German word U-Boot, a shortening of Unterseeboot. Austro-Hungarian Navy submarines were also known as U-boats.

The attack on Orleans was a naval and air action during World War I on 21 July 1918 when a German submarine fired on a small convoy of barges led by a tugboat off Orleans, Massachusetts, on the eastern coast of the Cape Cod peninsula. Several shells fired during the engagement likely missed their intended maritime or aircraft targets and fell to earth in the area around Orleans, giving the impression of a deliberate attack on the town.

Orleans is a town on Cape Cod in Massachusetts. The population was 6,307 at the 2020 census.