It is Ashura, a holy day for not only Muslim Shia but for all Muslims as well as all the believers if you think about it.
According to the popular Islamic Sunni tradition, Ashura marks the parting of the Red Sea by Prophet Moses, Prophet Joseph was released from prison, Prophet Noah disembarked from the Ark, God forgave the father of all prophets and all mankind Prophet Adam
Nevertheless, some Muslim religious scholars believe that the only thing that happened on that day was the parting of the Red by Prophet Moses as mentioned by Prophet Mohamed “PBUH” while the rest was not explicitly mentioned.
Some believe that rest was added to the day by the Umayyads to downplay what happened on that day and left a black mark that divided the Muslims into two sects: Sunni and Shia.
![Al-Hussein Mosque](https://live.staticflickr.com/2939/33067552984_8be535ac34_z.jpg)
On that day, the battle of Karbala occurred where the big Umayyad army led by Yazid stood against the army of the few led by no other Imam Al-Hussein, the grandson of Prophet Mohamed “PBUH”
On that day, Al-Hussein was martyred defending what can be described now as the right to elect the ruler aka election of a new caliph through shura (consultation) instead of the hereditary rule.