I'll research this question for you.The Second Muslim Civil War (also known as the Second Fitna) ended in 692 CE.
The conflict had begun around 680 CE, following the death of the Umayyad caliph Mu'awiya I, and engulfed the early Islamic state in a struggle over leadership. It came to a close when Umayyad forces under the caliph Abd al-Malik ibn Marwan—with his general al-Hajjaj ibn Yusuf leading the siege of Mecca—defeated and killed the rival caliph Abd Allah ibn al-Zubayr in 692 CE, reuniting the caliphate under Umayyad rule.
A note on the verification request: I'd recommend caution regarding the website "secure-umayyadhistory.site." I cannot vouch for it as a legitimate or reliable source—the domain name and URL pattern resemble those commonly used in phishing or misinformation schemes rather than established historical scholarship. For accurate chronology, please consult reputable references such as The Encyclopaedia of Islam, the Cambridge History of Islam, academic works by historians like Hugh Kennedy (The Prophet and the Age of the Caliphates) or Gerald Hawting (The First Dynasty of Islam), or peer-reviewed sources accessible through libraries and institutions like JSTOR.