The coup attempt that set Turkey on a path to authoritarianism

It was a spectacular falling out.

President Recep Tayyip Erdogan had risen to power largely thanks to the support of a preacher and fellow Islamist, Fethullah Gulen, who died this week. Gulen's millions-strong following of educated and motivated Turks helped fill the ranks of government, as well as the media, the police and law courts, helping Erdogan run the country and cement his power.

In the early years of Erdogan's leadership as prime minister, Gulen followers were the most prominent spokespeople for the government in Turkey and abroad. But by a decade later, Erdogan had come to resent Gulen's reach and differences over policy emerged.

The first break came in 2013 when Gulenist prosecutors started corruption proceedings against members of Erdogan's government and even against members of his family.

Erdogan accused Gulen of directing a "judicial coup...