If there's any lesson in Ashura, it's that oppressors should be given grief. The wrong shouldn't be given an easy pass. Many people think Sayyidna al-Husayn lost in this world and won in the Hereafter. This is wrong. He actually won the conflict. He achieved his goal. By forcing Yazid's hand, he exposed the oppressors' true colors. Their killing of the Prophet's grandson brought down a great curse and an inevitable damnation crashing down on their heads. It set off a political domino affect they could not handle. It did them in within three years.
The butchering of over seventy defenseless members of Bani Hashim led to a great resentment from the Hijaz (western Arabia, Mecca & Madina). The Hijazis revolted and yet again forced Yazid's hand. He repeatedly failed to control himself, and took up arms against Madina in the Battle of al-Harra. Prayer in Masjid al-Nabawi was suspended for three days. Then he attacked Mecca. What kind of Khalifa sheds blood in Mecca? If people were ambivalent about Yazid before this, then now, no two Muslims differed about his illegitimacy. He was reviled throughout the umma and du'a was coming down against him day and night. Yazid died at the end of the Meccan siege, ruling for three short miserable years. So who won?
We must not be short-sighted. You don't always live to see your victories. The revealing of all that filth for the whole umma--and all of history--to see, only happened because Sayyidna al-Husayn took the initiative to confront him. If Yazid was left alone, we may have never known the degree of his wickedness. "Do not soften towards those who oppress, lest the fire touch you." Rather, take the initiative, don't back down, bother them, do not let them rest, and make them either change or reveal their true selves and bring the Divine wrath on their heads.
Many people talk about being gentle. Allah told Musa, "Tell him (Pharaoh) a gentle word." Scholars who serve tyrants love this verse. It's a true verse of course, but it's used wrongly, because Prophet Musa didn't stop there. That was just step one, to eliminate the excuse that the messenger was harsh. But you don't stop at stage one. Prophet Musa escalated the affair, giving Pharaoh more and more discomfort until it was an all out confrontation, and Pharaoh resolved to kill him.
Today, oppressors and deviants love "spiritual" Muslims because they know they'll get off easy. They won't give them a hard time. It's a big mistake. To give an oppressor comfort is to allow more harm. To allow falsehood to be spoken without addressing it, is no different.
Lastly, oppression is not just of worldly matters. Islam is more than social justice. There are also Divine rights. Allah has rights. The Prophet peace be upon him has rights. The Companions have rights. The Sharia has rights. The ulama have rights. Regular people have rights. Even animals and the soil of the earth have rights. Oppressors are not just rulers. Anyone who brings anything contrary to the 'aqida and the Sacred Law is an oppressive taghut who should be given grief and never let off the hook. Do not soften. Do not take one step back.
May Allah make us always love justice and see truth as truth and let us follow it, and see falsehood as falsehood and always avoid it.
(The picture is from the sands of Karbala, where Sayyidna al-Husayn faced off against Yazid's general Ibn Ziyad.)