People gather at city hall and students march in anger at arrest of Ekrem İmamoğlu, a likely opposition candidate for presidency

Outside Istanbul’s city hall on Wednesday night a mass of protesters gathered in the freezing air to defy a city-wide ban on gatherings. A banner bearing a portrait of the Istanbul mayor, Ekrem İmamoğlu, giving a speech alongside the words “sovereignty belongs unconditionally to the nation” covered part of the facade of his now vacant office.

In dawn raids that morning police had detained İmamoğlu, the only contender seen as capable of defeating Recep Tayyip Erdoğan in presidential elections. For many residents of Turkey’s largest city, the arrest symbolised how far the state was willing to go to remove a perceived threat to the incumbent president.