The ship was tasked to protect Allied shipping off the coasts of North and South America from German commerce raiders after World War I began in August 1914. She briefly encountered a German light cruiser in the West Indies a few days after the war began, but the battle was inconclusive. A few months later, "Bristol" played a minor role in the Battle of the Falkland Islands in December by sinking some of the colliers belonging to the German East Asia Squadron. After a lengthy refit in mid-1915, the ship was transferred to the Adriatic Force, where she participated in the Battle of the Strait of Otranto in 1917. "Bristol" returned to her former task of patrolling off the east coast of South America, after a brief time escorting convoys off West Africa in early 1918, and continued to do so after the end of the war. She was placed in reserve in mid-1919, listed for sale in 1920 and was sold for scrap in 1921.