They were organised by students for 5pm on 5 May 1960 in Kızılay, Ankara to protest against the ruling Democrat Party.
They mobilised others by word of mouth with the watchword "555k" - that is at 5pm on 5 May in Kızılay, but the details of exactly how or where the protest was to begin were unknown to those attending.
[3] At the agreed time, Cemal Süreya, Altan Öymen and their friends were ready for action but when none took initiative to start the protest they began it themselves around half past five.
"[3] The police eventually managed to get Menderes into a vehicle belonging to Hürriyet Ankara Representative Emin Karakuş.
As soon as he was safely inside, Karakuş accelerated, broke through the crowd and left the square.
(According to some rumors, the person he spoke to was former CHP Chairman Deniz Baykal, a student at that time, or alternatively, according to the poet Cemal Süreya, it was Vedat Dalokay).
It was forbidden for more than 10 people to gather in Ankara; broadcast bans were brought in one after another; and those who took part in the protests were detained.
The statements of DP members, especially Menderes, became much harsher; indeed he called on his supporters to "punish" the protesters.
[3] About 20 days after the 555K protests, on May 27, the 1960 Turkish coup d'état took place, the first military intervention in the history of the republic.