Siege of Tsingtao
In December 1913, Katō returned to sea as commander-in-chief of the Second Fleet. With the start of World War I, the IJN 2nd Fleet was deployed to the Siege of Tsingtao. At Tsingtao, Katō commanded a fleet of four battleships, two cruisers, 15 destroyers along with submarines, torpedo boats and other auxiliary vessels.