According to official history, he was killed on the orders of his brother Svyatopolk, just as Prince Gleb of Murom was killed after that. Subsequently, he was canonized together with his brother Gleb by the Russian Orthodox Church as passion-bearers – Saints Boris and Gleb.[1]wikipedia
One of the first monuments of ancient Russian literature is devoted to the history of Boris and Gleb: the “Tale” by Jacob Chernorizets and the “Reading” by Nestor the Chronicler. Many temples and monasteries were built in honor of the brothers.
When the devil, the primordial enemy of all that is good in people, saw that Saint Boris placed all his hope in God, he began to intrigue and, as in ancient Cain’s times, plotting fratricide, tempted Svyatopolk. He guessed the thoughts of Svyatopolk, truly the second Cain: after all, he wanted to kill all the heirs of his father in order to seize all power alone. – The Legend of Boris and Gleb
The beginning of the civil strife
Having received news of the deaths of Boris and Gleb, Drevlyansky Prince Svyatoslav left his capital and tried to flee to the Carpathians, but was overtaken by the troops of Svyatopolk sent after him and died in battle.
Death of Boris Vladimirovich
The official version – is the murder of Boris on the orders of Svyatopolk
In 1015, his father Vladimir Svyatoslavich fell ill, and Boris was called to Kyiv. Soon after his arrival, it became known about the invasion of the Pechenegs, and his father sent him with a squad to repel them. Boris did not meet the Pechenegs anywhere and, returning back, stopped on the Alta River.

During the stay, a messenger from Kyiv arrived at Boris and told him about the death of his father. After the news that Svyatopolk had seized power, Boris burst into tears. The chronicles contain the following lines of his reasoning:
“…to whom to tell this bitter sadness? Brother, whom I revered as a father? But he, I feel, cares about worldly fuss and plots my murder. If he sheds my blood and decides to kill me, I will be a martyr before my Lord.”
After that, an envoy from Svyatopolk arrived and conveyed a message:
“Brother, I want to live with you in love and I will add more possessions to your lands inherited from our father” – Svyatopolk the Accursed
Simultaneously with assurances of love and friendship, Svyatopolk sent assassins to Boris – the boyars from Vyshgorod with Putsha at their head.
The army commanded by Prince Boris during the campaign against the Pechenegs offered to take the throne of Kyiv from Svyatopolk, but Boris did not agree:
“And the squad said to him: “Go, sit in Kyiv on your father’s princely table – after all, all the soldiers are in your hands.”
He answered them: “I cannot raise my hand against my brother, whom I honor as a father.”
Hearing this, the soldiers dispersed, and he was left only with his closest servants … “
Putsha with the boyars came to Alta, to the tent of Boris. On the night of 24 (30) July; Hearing the singing of psalms coming from the tent, Putsha decided to attack after Prince Boris fell asleep.
The murderers wrapped Boris, still breathing, in a tent canvas and took him to Kyiv. Riding a wagon past the forest, Boris suddenly began to raise his head. When Svyatopolk was informed that his brother was still alive, the new prince of Kyiv sent two Varangians to finish him off, which they did, piercing Boris in the heart with a sword. The body of Boris was secretly brought to Vyshgorod and buried there in the church of St. Vasily.

Hallmarks illustrated
“Life in the Icon of the Holy Princes Boris and Gleb”
Alternative version – from Scandinavian sagas
In 1834, Professor of St. Petersburg University, Osip Senkovsky, translated into Russian the “Saga of Eymund” (“Eymund’s strand”). He discovered there that the Varangian Eimund, along with his retinue, was hired by Yaroslav the Wise. The saga tells how King Yarisleif (Yaroslav) fights with King Burisleif. In the course of the narration of the saga, Burisleif is killed by the Vikings on the orders of Yarisleif. Some researchers suggest under the name “Burisleif” Boris, others – the Polish king Boleslav, whom the saga confuses with his ally Svyatopolk.
Then, on the basis of the Eymund saga, some researchers supported the hypothesis that Boris was killed by the Varangians sent by Yaroslav the Wise in 1017. This is indirectly confirmed by the fact that Yaroslav, Bryachislav and Mstislav refused to recognize Svyatopolk as the legitimate prince in Kyiv. Only two brothers – Boris and Gleb – declared their allegiance to the new Kyiv prince and pledged to “honor him as their father,” and it would be very strange for Svyatopolk to kill his allies.
Until now, this hypothesis has both its supporters and opponents.[2]wikipedia
Memory and veneration
Boris, under the name Roman Russian, is included in the list of saints of the Roman Catholic Church.
Truly you are Caesars to Caesars and princes to princes, for with your help and protection our princes defeat all opponents and are proud of your help. You are our weapons, the lands of Russian protection and support, double-edged swords, with them we overthrow the insolence of the filthy and trample the devilish machinations on earth. – The Legend of Boris and Gleb
“The Tale of Boris and Gleb”
The legend was written in the middle of the XI century in the last years of the reign of Yaroslav the Wise. Later, the Tale was supplemented by a description of the miracles of the saints (“The Tale of Miracles”), created in 1089-1115 by successively three authors. In this form, the text is contained in the oldest known list in the Assumption collection of the late XII – early XIII centuries.
In total, the “Legend of Boris and Gleb” has been preserved in more than 170 lists. Based on the research of Metropolitan Macarius and M. P. Pogodin, the author of the Tale is considered to be Jacob Chernorizets.[3]wikipedia
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1. Boris and Gleb are honored by Jesus Christ with crowns of martyrdom
2. Boris goes to the Pechenegs
“Reading about Boris and Gleb”
“Reading” is written in the hagiographic genre, the author describes facts unknown from the annals from Boris’s youth (the dream of martyrdom under the influence of reading the lives of the saints, evasion of marriage and marriage only at the insistence of his father: “not lust for the sake of bodily”, but “law for the sake of the Tsar’s and the obedience of the father”).[4]wikipedia