Pope Gregory VII died in 1085, having named three potential successors. The first, Desiderius, was a pious man who had devoted his life to not being in the public eye, and remained in the office as Victor III for a mere 130 days, after which Odo of Chatillon was made pope by acclamation, taking the name Urban II.
Urban's first challenge was the antipope Clement III, who had been installed by Holy Roman Emperor Henry IV in 1085 after Henry's clash with Gregory over the Investiture Controversy (see Gregory's link above). Urban had to avoid Rome because of Clement, but he traveled around northern Italy and France, holding synods to promote reforms against simony, clerical marriages, and issues of the Holy Roman Emperor and the antipope. (Clerical marriages—rather, the practice of keeping mistresses—were dealt with in England and France simply by instituting a heavy tax on mistresses.)
He became involved in political issues when he supported the rebellion of Prince Conrad against his father, Henry IV. He helped arrange the marriage of Conrad to Maximilian, the daughter of Count Roger I of Sicily (she brought a large dowry that helped Conrad in the fight against Henry).
He also negotiated a compromise between Anselm of Bec and William II of England, which brought him England's support against the antipope.
Urban's most profound undertaking was to preach the Crusade in 1095 (see illustration), starting a papal policy of trying to assert control over the Holy Land that lasted for centuries. He was motivated by a request from the Byzantine Emperor Alexios I Comnenos, asking for help against the Turks. Urban offered remission of all sins for those who "took up the Cross."
He also gave Roger of Sicily the authority to appoint bishops, to forward the church revenues to Urban, and to sit in judgment over ecclesiastical issues—the exact opposite of what the Investiture Controversy with Henry IV was supposed to resolve! Other secular rulers did not get these privileges, which led to problems later with Roger's heirs.
Urban died in 1099, in Rome. Had he, then, eliminated the antipope Clement? Not really. Clement outlived and (in some sense) out-reigned Urban. Let's look at the anti-papacy of Clement II tomorrow.