K'awiil of Calakmul, while Copán was one of Tikal's oldest allies. The timing of this visit by the king of Calakmul is highly significant, falling between the accession of K'ak' Tiliw Chan Yopaat to the throne of Quiriguá as a vassal of Copán and the outright rebellion that was to follow. This strongly suggests that Calakmul sponsored Quiriguá's rebellion in order to weaken Tikal and to gain access to the rich trade route of the Motagua Valley. It is likely that contact with Calakmul had been initiated soon after K'ak' Tiliw Chan Yopaat acceded to the throne. In 738 K'ak' Tiliw Chan Yopaat captured the powerful but elderly king of Copán, Uaxaclajuun Ub'aah K'awiil. An inscription at Quiriguá, although difficult to interpret, suggests that the capture took place on 27 April 738, when Quiriguá seized and burned the wooden images of Copán's patron deities. The captured lord was taken back to Quiriguá and on 3 May 738 he was decapitated in a public ritual. In the Late Classic, alliance with Calakmul was frequently associated with the promise of military support. The fact that Copán, a much more powerful city than Quiriguá, failed to retaliate against its former vassal implies that it feared the military intervention of Calakmul. Calakmul itself was far enough away from Quiriguá that K'ak' Tiliw Chan Yopaat was not afraid of falling directly under its power as a full vassal state, even though it is likely that Calakmul sent warriors to help in the defeat of Copán. The alliance instead seems to have been one of mutual advantage: Calakmul managed to weaken a powerful ally of Tikal while Quiriguá gained its independence. Collapse Five large stelae were raised in 741, although the name of the king responsible is illegible on all of them and he has been labelled as Ruler Y. Calakmul's presence in the wider Maya area continued to wane, with two of the city's major allies suffering defeats at the hands of Tikal. El Peru was defeated in 743 and Naranjo a year later and this resulted in the final collapse of Calakmul's once powerful alliance network, while Tikal underwent a resurgence in its power. In 751 Ruler Z erected a stela that was never finished, paired with another with the portrait of a queen. A hieroglyphic stairway mentions someone called B'olon K'awiil at about the same time. B'olon K'awiil was king by 771 when