After his victory on 29 July 1014, when a large part of the Bulgarian army was destroyed, Basil II marched westwards and seized the small fortress of Matsukion near Strumitsa, but the town itself remained in Bulgarian hands. That is why the Byzantine Emperor sent an army led by one of his most capable generals, Theophylactus Botaniates, to destroy the palisades to the south of the town, which had been built by Samuil before the campaign. Thus he would clear the way of the Byzantines to Thessaloniki through the valley of the Vardar river.
He [Botaniates] marched on and the Bulgarians who guarded the surroundings allowed him to make his way undisturbed. But when he was preparing to go back to the Emperor after he had fulfilled his orders, he was ambushed in a long gorge. When he entered he was surrounded and fired with stones and arrows; he was killed and no one could help him...
The historian Vasil Zlatarski specifies the battlefield at the Kosturino gorge between the mountains Belasitsa and Plavush. The Byzantines could not organize their defense in the narrow pass and were annihilated. Most of their troops perished including their commander. According to bishop Michael of Devol, Botaniates was killed by the heir to the Bulgarian throne Gavril Radomir, who pierced the Byzantine general with his spear.[1][2] Upon the news of that unexpected and heavy defeat, Basil II was forced to immediately retreat eastwards and not through the planned route via Thessaloniki. He also lifted the siege of Strumitsa. In order to break the spirit of the Bulgarians, Basil II blinded thousands of soldiers previously captured at Kleidion and sent them to Samuil.[3]
Подбрани извори за българската история, Том II: Българските държави и българите през Средновековието, Изд. "ТАНГРА ТанНакРа ИК", София 2004, ISBN954-9942-40-6, с. 66-67
Мутафчиев, Петър, Книга за българите, Издателство на БАН, София 1992, ISBN954-430-128-3, с. 118-119
Златарски, Васил, История на българската държава през средните векове, том 1, част 2, Академично издателство "Марин Дринов", София 1994, ISBN954-430-299-9 (т. 1, ч. 2), с. 738 (с. 697-700 в електронно издание)
Пириватрич, Сърджан, Самуиловата държава. Обхват и характер, Изд. група "АГАТА-А", София 2000, ISBN954-540-020-X, с. 137
Гюзелев, Васил, България от втората четвърт на Х до началото на ХІ век, с. 71, 74, в: Димитров, Илчо (ред.), Кратка история на България, изд. "Наука и изкуство", София 1983
Zlatarski, Vasil, History of Bulgaria in the Middle Ages (Istoria na balgarskata darzhava prez srednite vekove, История на българската държава през средните векове), in Bulgarian, Vol. 1, Part 2, Marin Drinov Academic Publishers, Sofia, 1994, ISBN954-430-299-9 (That work can be found in the Internet, taken from the site "Books for Macedonia" (in Bulgarian)Archived 2014-07-21 at the Wayback Machine on 29.01.2008)
Gyuzelev, Vasil, Bulgaria from the second quarter of the tenth century to the beginning of the 11th century, (Balgaria ot vtorata chetvart na X do nachaloto na XI vek, България от втората четвърт на Х до началото на ХІ век), in Bulgarian, In: Dimitrov, Ilcho (Ed.), Short History of Bulgaria (Kratka istoria na Balgaria, Кратка история на България), in Bulgarian, Science and Arts Publishers, Sofia 1983
