Turkish President Recep Tayyip Erdogan leads Saturday prayers at Istanbul's iconic Hagia Sophia mosque before entering the election battle of his political life against a powerful secular rival. The 69-year-old will be emulating a ritual that Ottoman Sultans performed before they led their men off to war as he braces for Sunday's parliamentary and presidential ballot. Erdogan has never faced a more energised or united opposition than the one spearheaded by retired civil servant Kemal Kilicdaroglu and his disparate alliance of six parties. The Turkish leader excelled at splitting his rivals and forging unlikely unions while winning one national election...