On 22 September 1197 a substantial German army under the command of Archchancellor Conrad of Mainz and Marshal Henry of Kalden landed at Acre, where their presence aroused the displeasure of the French forces of Queen Isabella of Jerusalem. As the German Princes denied the authority of Henry of Kalden, they elected Duke Henry of Brabant their commander and the crusaders proceeded to Tyre, initiating a campaign to expel the Muslims from Beirut and to subject the Levant coast up to Tripoli. They captured the wealthy and important city of Sidon and on October 24 entered Beirut. With the support of the Princes, Emperor Henry's vassal King Amalric of Cyprus married Queen Isabella and was crowned King of Jerusalem  in 1198. The crusaders continued their campaign and by reconquering the estates around Byblos Castle  restored the land link to the County of Tripoli. They even marched against Damascus and laid siege to Toron, when news of the emperor's death reached them. By July 1198 most of the nobles had returned home to get their fiefs confirmed by Henry's successor. The remaining crusaders concluded another armistice in June 1198 with the Ayyubid emir Al-Adil I, who acknowledged the rule of King Amalric II over the reconquered lands. In his capacity as King of Jerusalem, Amalric enfeoffed the Lordship of Beirut to John of Ibelin and the Lordship of Sidon to Reginald Grenier. On his way back to Germany, Archbishop Conrad of Mainz in January 1198 crowned Prince Leo of Cicilia King of Armenia in Tarsus.
Question: How many months did the campaign take to completion?
Answer: 4