In January 1978, the first major demonstrations to over throw Shah Mohammad Reza Pahlavi began. Officially , Iran became the Islamic Republic. Exactly on the 1st April 1979. So, Iranians perform nation wide celebration on this day.
PASSING OF AYATOLLAH KHOMEINI 14TH KHORDAD:
Grand Ayatollah Ruhollah Khomeini passed a way on the 3rd of June 1989, at 22:20 IRST, after spending 11 days at private hospital, near His residency after repeated heart failure ( aged 86).
The founder of the Islamic republic was buried near the Behesht-e-Zahra,the main graved of Tehran.So,this day is mourned by all Iranians Across the country.
THE 15TH OF KHORDAD UPRISING:
On the 5th of June 1963, the demonstrations were protests in Iran against the arrest of Ayatollah-Ruhollah-Khomeini, it was the beginning of Islamic revolution which was to change Iran’s destiny.