[5] According to Thietmar of Merseburg, Sviatopolk's wife, son and Reinbern (former bishop of Kolberg, modern Kołobrzeg) were also imprisoned; the latter reportedly died in captivity.
[3] The Primary Chronicle (PVL), the most frequently cited, but not the most reliable source about the conflict, was written about 100 years later in the 1110s, possibly commissioned by Yaroslav's descendants.
[11][13] Curiously, neither Boris nor Gleb resisted their fate, but accepted their death as an imitation of the Arrest of Jesus at Gethsemane.
[11] This narrative later became the basis of the cult of the princely saints Boris and Gleb, which Yaroslav evidently helped to create and spread in order to enhance the reigning clan's legitimacy.
Then he began to reflect how he would kill all his brethren, and rule alone in Rus'.According to the Primary Chronicle (PVL), Yaroslav was informed about the events in Kiev by his sister Predslava Volodimerovna.
[18][19][20][e] There are also textual variations between the Laurentian (Lav) and Academic (Aka) manuscripts of version B, which say that Sviatopolk's men were on their way to kill Boris and Gleb, and the Hypatian (Ipa), Khlebnikov (Xle) and Radziwiłł (Rad) manuscripts, which state that Boris had already been killed, and Sviatopolk's men were now on their way to Gleb.
[21][22] Moreover, he claims that Sviatopolk (Sventipulk) fled to his father-in-law Bolesław (Boleslav) in Poland immediately after the death of Volodimer (Vladimir), while the realm was divided between "his (two) other sons".
Við hann átti Eymundr fimm bardaga, en í inum síðasta var Burizleifr handtekinn ok blindaðr ok færðr konungi.
[23] On the other hand, other scholars claim that Burizleifr may have been based on duke Bolesław I of Poland instead, and that the Eymund Saga should be considered largely or entirely fictional.
[23] It is now impossible to say with complete certainty what really happened, but the evidence of a late and obscure foreign source still hardly outweighs the established version of Rus' chronicles.
The main textual witnesses of the Primary Chronicle provide conflicting accounts on details (in lines 141.17–142.22) of the Battle of Liubech.
[27][g] It's unclear whether the Chronicle Yaroslav's arrival was causally linked to the churches burning or not, but Thietmar reported that only Saint Sophia Cathedral, Kyiv had suffered severe damage from an accidental fire in 1017.
Realising that it was only a matter of time before Bolesław I would use force to support his son-in-law, Yaroslaw concluded an agreement against Bolesław I with Holy Roman Emperor Henry II, who had been at war with Poland since July 1015, and he himself moved with his army to Berestia in 1017, simultaneously with Henry II's invasion of Poland.
[citation needed] In early 1018, Bolesław I concluded peace with Emperor Henry II on the status quo ante and turned his attention to the east.
[31]In summer 1018, Bolesław I intervened on behalf of his son-in-law Sviatopolk, and their combined troops and the opposing forces of Yaroslav encamped on both sides of the Western Bug (a tributary to the Vistula) near the town of Volyn.
[34] The Primary Chronicle claims that Sviatopolk ordered the secret killing of the Lyakh (Polish) garrison, causing Bolesław I to evacuate from Kiev in a hurry, taking the property and boyars of Yaroslav and his sisters as hostages with him.
[33] Thietmar, on the other hand, reports that Bolesław "enthroned his son-in-law" and "returned joyfully" (Latin: hilaris rediit) to Poland.
[k] Thietmar's Chronicon contains no reports of Polish troops garrisoning Kiev or other cities that were massacred, nor that Bolesław fled with lots of booty and hostages.
In the Battle of the Alta River (1019), that took place at the supposed site where Boris was killed, Yaroslav defeated Sviatopolk and secured the Kievan throne.