Imam Hussain (as)
The battle of Karbala (10th Muharram 61AH) was when the Prophet beloved grandson, the leader of the youth of paradise, Imam Hussain (as), was martyred in the name of Islam and the truth.
In the scorching sun in the desert of modern day Iraq, Imam Hussain (as) army outnumbered by Yazid's military and also very thirsty as the opposition had blocked them from the water. Yet they continued fighting until their lives were taken in the name of Islam.