Richard I (8 September 1157 - 6 April 1199) was King of England from 1189 until his death. He also ruled as Duke of Normandy, Aquitaine and Gascony, Lord of Cyprus, Count of Poitiers, Anjou, Maine, and Nantes, and was overlord of Brittany at various times during the same period. He was the third of five sons of King Henry II of England and Duchess Eleanor of Aquitaine. He was known as Richard Coeur de Lion or Richard the Lionheart because of his reputation as a great military leader and warrior.

Richard had already taken the cross as Count of Poitou in 1187. His father and Philip II had done so at Gisors on 21 January 1188 after receiving news of the fall of Jerusalem to Saladin. After Richard became king, he and Philip agreed to go on the Third Crusade, since each feared that during his absence the other might usurp his territories.  Richard swore an oath to renounce his past wickedness in order to show himself worthy to take the cross. He started to raise and equip a new crusader army. He spent most of his father's treasury (filled with money raised by the Saladin tithe), raised taxes, and even agreed to free King William I of Scotland from his oath of subservience to Richard in exchange for 10,000 marks. To raise still more revenue he sold the right to hold official positions, lands, and other privileges to those interested in them. Those already appointed were forced to pay huge sums to retain their posts. William Longchamp, Bishop of Ely and the King's Chancellor, made a show of bidding PS3,000 to remain as Chancellor. He was apparently outbid by a certain Reginald the Italian, but that bid was refused.  Richard made some final arrangements on the continent. He reconfirmed his father's appointment of William Fitz Ralph to the important post of seneschal of Normandy. In Anjou, Stephen of Tours was replaced as seneschal and temporarily imprisoned for fiscal mismanagement. Payn de Rochefort, an Angevin knight, was elevated to the post of seneschal of Anjou. In Poitou the ex-provost of Benon, Peter Bertin, was made seneschal, and finally in Gascony the household official Helie de La Celle was picked for the seneschalship there. After repositioning the part of his army he left behind to guard his French possessions, Richard finally set out on the crusade in summer 1190. (His delay was criticised by troubadours such as Bertran de Born.) He appointed as regents Hugh de Puiset, Bishop of Durham, and William de Mandeville, 3rd Earl of Essex--who soon died and was replaced by Richard's chancellor William Longchamp. Richard's brother John was not satisfied by this decision and started scheming against William. When Richard was raising funds for his crusade, he was said to declare, "I would have sold London if I could find a buyer".  In September 1190 Richard and Philip arrived in Sicily. After the death of King William II of Sicily his cousin Tancred had seized power and had been crowned early in 1190 as King Tancred I of Sicily, although the legal heir was William's aunt Constance, wife of the new Emperor Henry VI. Tancred had imprisoned William's widow, Queen Joan, who was Richard's sister, and did not give her the money she had inherited in William's will. When Richard arrived he demanded that his sister be released and given her inheritance; she was freed on 28 September, but without the inheritance. The presence of foreign troops also caused unrest: in October, the people of Messina revolted, demanding that the foreigners leave. Richard attacked Messina, capturing it on 4 October 1190. After looting and burning the city Richard established his base there, but this created tension between Richard and Philip Augustus. He remained there until Tancred finally agreed to sign a treaty on 4 March 1191. The treaty was signed by Richard, Philip and Tancred. Its main terms were:  Joan was to receive 20,000 ounces (570 kg) of gold as compensation for her inheritance, which Tancred kept.  Richard officially proclaimed his nephew, Arthur of Brittany, son of Geoffrey, as his heir, and Tancred promised to marry one of his daughters to Arthur when he came of age, giving a further 20,000 ounces (570 kg) of gold that would be returned by Richard if Arthur did not marry Tancred's daughter.  The two kings stayed on in Sicily for a while, but this resulted in increasing tensions between them and their men, with Philip Augustus plotting with Tancred against Richard. The two kings finally met to clear the air and reached an agreement, including the end of Richard's betrothal to Philip's sister Alys (who had supposedly been the mistress of Richard's father Henry II).  In April 1191 Richard left Messina for Acre, but a storm dispersed his large fleet. After some searching, it was discovered that the ship carrying his sister Joan and his new fiancee Berengaria was anchored on the south coast of Cyprus, along with the wrecks of several other vessels, including the treasure ship. Survivors of the wrecks had been taken prisoner by the island's ruler, Isaac Komnenos.  On 1 May 1191 Richard's fleet arrived in the port of Lemesos (Limassol) on Cyprus. He ordered Isaac to release the prisoners and treasure. Isaac refused, so Richard landed his troops and took Limassol. Various princes of the Holy Land arrived in Limassol at the same time, in particular Guy of Lusignan. All declared their support for Richard provided that he support Guy against his rival, Conrad of Montferrat.  The local magnates abandoned Isaac, who considered making peace with Richard, joining him on the crusade, and offering his daughter in marriage to the person named by Richard. Isaac changed his mind, however, and tried to escape. Richard's troops, led by Guy de Lusignan, conquered the whole island by 1 June. Isaac surrendered and was confined with silver chains because Richard had promised that he would not place him in irons. Richard named Richard de Camville and Robert of Thornham as governors. He later sold the island to the master of Knights Templar, Robert de Sable, and it was subsequently acquired, in 1192, by Guy of Lusignan and became a stable feudal kingdom.  The rapid conquest of the island by Richard is more important than it may seem. The island occupies a key strategic position on the maritime lanes to the Holy Land, whose occupation by the Christians could not continue without support from the sea. Cyprus remained a Christian stronghold until the battle of Lepanto (1571). Richard's exploit was well publicised and contributed to his reputation, and he also derived significant financial gains from the conquest of the island. Richard left Cyprus for Acre on 5 June with his allies.Answer this question using a quote from the following article:

Who was involved?
After Richard became king, he and Philip agreed to go on the Third Crusade, since each feared that during his absence the other might usurp his territories.