Dorostolon (Silistra). During his retreat, the emperor was surrounded and worn down by the Pechenegs, who forced him to sign a truce and to pay protection money. In 1090 the Pechenegs invaded Thrace again, while Tzachas, the brother-in-law of the Sultan of Rum, launched a fleet and attempted to arrange a joint siege of Constantinople with the Pechenegs. Alexios overcame this crisis by entering into an alliance with a horde of 40,000 Cumans, with whose help he crushed the Pechenegs at Levounion in Thrace on 29 April 1091. This put an end to the Pecheneg threat, but in 1094 the Cumans began to raid the imperial territories in the Balkans. Led by a pretender claiming to be Constantine Diogenes, a long-dead son of the Emperor Romanos IV, the Cumans crossed the mountains and raided into eastern Thrace until their leader was eliminated at Adrianople. With the Balkans more or less pacified, Alexios could now turn his attention to Asia Minor, which had been almost completely overrun by the Seljuq Turks. Byzantine–Seljuq Wars and the First Crusade By the time Alexios ascended the throne, the Seljuqs had taken most of Asia Minor. Alexios was able to secure much of the coastal regions by sending peasant soldiers to raid the Seljuq camps, but these victories were unable to stop the Turks altogether. As early as 1090, Alexios had taken reconciliatory measures towards the Papacy, with the intention of seeking western support against the Seljuqs. In 1095 his ambassadors appeared before Pope Urban II at the Council of Piacenza. The help he sought from the West was simply some mercenary forces, not the immense hosts that arrived, to his consternation and embarrassment, after the pope preached the First Crusade at the Council of Clermont later that same year. This was the People's Crusade: a mob of mostly unarmed pilgrims led by the preacher Peter the Hermit. Not quite ready to supply this number of people as they traversed his territories, the emperor saw his Balkan possessions subjected to further pillage at the hands of his own allies. Eventually Alexios dealt with the People's Crusade by hustling them on to Asia Minor. There, they were massacred by the Turks of Kilij Arslan I at the Battle of Civetot in October 1096. The "Prince's Crusade", the second and much more formidable host of crusaders, gradually made its way to Constantinople, led in sections by Godfrey