What deadly influenza pandemic spread worldwide in 1918?

What deadly influenza pandemic spread worldwide in 1918? It was the Spanish flu, also called the 1918 influenza pandemic.

The pandemic was caused by an influenza A virus associated with the H1N1 subtype. It spread rapidly across continents during the final year of World War I, aided by troop movements, crowded military camps, wartime travel, and censorship of news about outbreaks. Spain, which was neutral in the war, reported extensively on the disease, helping give rise to the misleading name “Spanish flu.”

Unlike ordinary seasonal influenza, the 1918 pandemic caused unusually high mortality among some healthy young adults as well as children and older people. Estimates commonly place the worldwide death toll at tens of millions, although the exact number is uncertain. The Russian flu, Hong Kong flu, and Asian flu were separate influenza pandemics or outbreaks from other periods, not names for the 1918 pandemic.