We will present some historical facts to understand how this despot attained power.
Certainly not preserving the Deen did not even come into the equation. The truth was one of Muawiya’s cohorts Mughira bin Shuba nominated his name in order to gain favor from his father to save his own seat of power. Ibn Jareer quotes from Shubi that when Mughira bin Shuba caught wind of plans to have him relieved of his governorship:-
“al-Mughirah then went to see Yazid, and proposed the acknowledgement to him. When Yazid conveyed that to his father, Muawiyah reappointed al-Mughira to al-Kufah ordering him to work for Yazid’s acknowledgement”.
History of Tabari, Volume 18 page 184
Prominent personalities were offered bribes as Ibn Katheer writes:
According to Zaid bin Bakkar, Ibrahim bin Muhammad bin AbdulAziz Az Zahari quotes from his father who quotes from his father that when Abdul Rahman refused to give bayya to Yazid, Mu’awiya sent Abdul Rahman one million dirhams. He returned the money by asking ‘Do you expect me to sell my religion for this world?”
Al Bidayah Wal Nihayah (Urdu), Vol 8 Page 891, Nafees Academy Karachi
Allamah Ibn Hajr Asqalani writes:
Muawiya demanded that Abdullah bin Umar give his allegiance to Yazid. He sent him hundred thousand dirhams but Abdullah bin Umar refused to take the money.
Fatah ul Bari, Volume 13 page 80
When bribery did not work as intended Muawiya resorted to coercion. According to Hafiz Ibn Katheer there were five well known personalities who refused to give their allegiance to Yazid.
Muawiyah himself traveled to the city of Medina, to call upon all five and threatened them with dire consequences should they refuse to pledge allegiance to his son.
Al Bidayah Wal Nihayah, Vol 7 page 79, the events of 57Hijri.
We read in Tareekh Kamil, Volume 3 page 455 Dhikr bayya Yazid:
“Five people rejected the bayya of Yazid. Mu’awiya approached Ayesha and said, ‘If these individuals don’t give bayya to Yazid then I will kill them’. Ayesha replied ‘I have also heard news that that you are threatening the Khalifah’s sons, in connection with the bayya to Yazid”.
We read in Tareekh Tabari, Volume 18 page 187 Events of 56 Hijri that Muawiyah summoned:
“Abd al Rahman bin Abu Bakr when he refrained from pledging allegiance to Yazid and was thereafter threatened as follows: “O Ibn Abi Bakr by what hand and foot do you come to disobey me?” He replied ‘I hope that it would be good for me’. Muawiyah responded ‘By God I intended to kill you’. He answered, ‘If you do so, may God cause a curse to follow you in this world for it and make you enter the fires in the next [world] for it”.
We read in Fatah ul Bar, Volume 13 page 80:
Nafee narrated that Mu’awiya wanted Ibn Umar to give Bayya to Yazid, but he (Ibn Umar) refused and said: ‘I don’t give bayya to two princes’. Then Mu’awyia sent 100,000 Dirham to him and he (ibn Umar) received it. Then he (Mu’awiya) sent a man to him (Ibn Umar) and he (the man) said to him (ibn Umar): ‘What is stopping you from giving bayya?’ He (ibn Umar) replied: ‘If this (money) is for that (bayya) then my faith is of low price’. When Mu’awyia died Ibn Umar gave bayya to Yazid.
Based on numerous historical sources, even before Imam Hussain (as) decided to go to Kufa, Yazid had started to hatch conspiracies as to how to force the Imam Hussain to pay his allegiance to this tyrant and dictator. After Muwaiya’s death, Yazid wrote to his governor in Madina Waleed bin Utbah.
“Be extremely harsh on Hussain, Abdullah bin Omer and Abdullah Ibn Zubair regarding my bayaat and don’t let the loose till they offer me their allegiance”.
Al Bidayah Wal Nihayah, Volume 8 page 1004, Nafees Academy Karachi
Then Waleed bin Utba consulted Marwan regarding the issue of Bayah to which Marwan answered:
“Before they learn about Muawiyah’s death, order them to offer Bayyat and if they refuse kill them”.
Al Bidayah Wal Nihayah, Volume 8 page 1004, Nafees Academy Karachi
The readers can make up their own minds based on the above historical facts and come to the conclusion that how Yazid and his Shia (helpers) wanted to kill everyone regardless of who they were so he could solidify his own tyrannical rule.