On the outbreak of the First World War, Carmania was requisitioned as an Armed Merchant Cruiser. Nine days after War was declared, she met and engaged the similarly armed German equivilant Cap Trafalgar. Opening fire simultaneously at three miles, the two liners closed to within 1,700 yards, Carmania alight from bow to stern after receiving seventy nine hits. However, the Cap Trafalgar was holed below the waterline and was sinking when smoke on the horizon warned of the approach of the German raider Kronprintz Wilhelm. Carmania made good her escape and the incident remains unique in the annals of modern warefare. She was broken up in 1932.