Our 3rd Imam, Imam Hussain (as) fought with Yazid ibn Muawiya in 61 AH to save Islam. Imam Hussein (as) was forced to fight Yazid's army because he would not give Bayat (oath of allegiance) to Yazid ibn Muawiya.

When Imam Hussein (as) was told that he had to give Bayat to Yazid otherwise he would be killed, Imam Hussein (as) replied that: a man like him could not give Bayat to a man like Yazid ibn Muawiya.

By saying this Imam Hussein (as) was trying to tell everyone that what Yazid believed in was totally opposite to what Imam Hussein (as) believed in. Yazid was the follower of Shaitan while Imam Hussein (as) was the follower of Allah (SWT).

Imam Hussein (as) knew that himself, his friends and family were to die in Karbala. He also knew that this was the only way that he could show to the other Muslims that Yazid who claimed to be a Muslim and protect Islam was in fact destroying it.

In Imam Hussein (as) army there were not just strong soldiers, that was not what was needed to get into the army of Imam Hussein (as). To get into the army of Imam Hussein (as) you needed to believe and act upon Islam.

Imam Hussein (as) wanted people, when they heard about the events of Karbala to know that it was not for power but for Islam and this is how to get into the army of Imam Hussein (as) you needed to be a believer and not a soldier. Imam Hussein's (as) army had all kinds of people:

Imam Hussein (as) had rich, noble men. He had freed slaves. He had old and young men. He had men who had done wrong and repented (e.g.Hazrat Hurr - the commander of Yazid ibn Muawiya army). He had pious men.

Whenever other Muslims heard about the events of Karbala, they would ask themselves, why it was that men from different backgrounds, different circumstances, different ways of life, all came together to fight and die with Imam Hussein (as).

Every Muslim regardless of his colour, his race, his background, his financial situation, his age, could identify himself with one martyr in the army of Imam Hussein (as) and through him understand why Imam Hussein (as) did what he did.

Imam Hussein (as) could not give Bayat to Yazid ibn Muawiya because it was against what he believed in. You should always stand by what you believe in. Imam Hussein (as) gave up his life for Islam. We as guardians of Islam should make sure that we keep Islam alive the way Imam Hussain (as) would have wanted.