He was killed on the tenth of Muharram (ashura) in the year 680 on the plain of Karbala, in what is now Iraq.
ashura is also a reminder that the eternal value of justice must be defended regardless of the odds of success.
This year, ashura, the culmination of the mourning ceremonies, will fall on December 27.
Although Shias are a minority in Pakistan, the shops along the route were closed that day, a national holiday known as ashura.
The Revolutionary Guard and the basij are determined to make sure that Muharram and ashura will not provide that opportunity.
It is greater than the day of Ramadan and the day of el-Adha and the day of ashura.
Islamic fast on the 10th day of Muharram, Arabic Ashura', literally "tenth."