The Rus had launched several raids against Constantinople, the greatest being in 860 & 941. These were dangerous Viking style raids. In 1043, despite good relations with the Romans, the Rus decided to try again. The heavy Rus casualties ended up littering the Roman beaches with the survivors massacred. Reviving the tradition of raids did not go so well.
In 1043 the Emperor Constantine IX Monomachos received news from his intelligence network that the Rus King Jaroslav the Wise was going to launch a sea raid against Constantinople. The Emperor took this threat very seriously, keeping in mind the great raids of the past. Allegedly the “pretext was a brawl in which a Rus’ noble had been killed by some Romans. Monomachos pleaded with the king that was no reason to disrupt good trading relations, but the massive armada sailed out anyway under the command of prince Volodymyr.” They would regret not listening to imperial warnings.
The barbarians arrived and “found Monomachos ready.” The Emperor had made sure all the Rus inside Constantinople had been arrested to make sure no sabotage or aid could come from within. “The Roman fleet met the enemy in the Bosporos. Advance fireships incinerated the lead longships, after which the main Roman fleet engaged and defeated the rest. 15,000 corpses were a later found on the beach. Survivors who reached the shore were cut down by the land army, which Monomachos had called up, and a force that tried to march back north along the Black Sea coast was defeated.”
Constantine Monomachos had prepared and scored an utterly decisive victory. The Rus never contemplated such an attack again. “Later Rus tradition tried to cover up the debacle by alleging their fleet was destroyed by a storm before reaching ‘Tsargrad (Constantinople’.” Sometimes Monomachos gets a tough assessment, but events like this show that he always tried to react militarily to foreign threats.
Source – The New Roman Empire: A History of Byzantium by Anthony Kaldellis
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