In 1928, Nasser went to Alexandria to live with his maternal grandfather and attend the city's Attarin elementary school. He left in 1929 for a private boarding school in Helwan, and later returned to Alexandria to enter the Ras el-Tin secondary school and to join his father, who was working for the city's postal service. It was in Alexandria that Nasser became involved in political activism. After witnessing clashes between protesters and police in Manshia Square, he joined the demonstration without being aware of its purpose. The protest, organized by the ultranationalist Young Egypt Society, called for the end of colonialism in Egypt in the wake of the 1923 Egyptian constitution's annulment by Prime Minister Isma'il Sidqi. Nasser was arrested and detained for a night before his father bailed him out.