Secondly, the alliance's provisions for mutual defence prompted Japan to enter World War I on the British side, attacking the German base at Tsingtao in 1914 and driving the Germans out of it (see Siege of Tsingtao).
The alliance's provisions for mutual defence prompted Japan to enter World War I on the British side, attacking the German base at Tsingtao in 1914 and driving the Germans out of it (see Siege of Tsingtao). This was secondly.