Mieceslav II., son of Boleslas Khrabrie (who had died 1025), was waging a hotly contested war with his brothers and the Kaiser Konrad II., gave an opportunity for regaining the Red Russian towns which perennially changed hands according to the respective strength and weakness of the two countries. [Sidenote: 1031] Yaroslav, in conjunction with his half-brother, invaded Poland and wrested back the lost territory. In 1034 died Mstislav, at the end of a day’s hunting, having shortly before lost his only son Evstaf. Of all the sons of Vladimir this intrepid warrior “with dark face and large eyes” seems most to have enchained the imagination of the national chronicler. Yaroslav, freed from the disquieting possibility of trouble which Mstislav must always have presented, made himself still more secure by seizing and imprisoning, on pretext of disaffection, Soudislav of Pskov, another member of the princely house. Shortly afterwards he was called upon to defend Kiev from an attack of the Petchenigs. Near the walls of the city Yaroslav joined issue with the barbarians, his vanguard consisting of Varangians, flanked right and left by the men of Kiev and Novgorod. After a battle which lasted till evening the Petchenigs broke and fled, leaving enormous numbers of dead on the field, and losing many more in crossing the rivers which impeded their flight. On the ground of this victory Yaroslav founded the Cathedral of S. Sofia, extending at the same time the boundaries of Kiev so as to include this building, and enclosing the city with a stone wall. Well might the Kievians rejoice as they watched the new works, which were alike the witness of their growing prosperity and a memorial of a past danger; they had at last grasped their nettle, and the might of the Petchenigs, which had hung so long like a menacing shadow ready at any moment to ride out of the steppe a grim reality, was for ever shattered. And as the new cathedral rose before them their hopes might soar to a point which would raise the mother of Russian cities to the level of Constantinople.