With Princess Olga's regency (945-962) we encounter the first Christian ruler of a unified Rus'. Many details of her own baptism and subsequent request for a Christian bishop from Germany have remained controversial until now, however. What can be said with some assurance, though, is that the date of 955 found in most chronicles of Old Rus' (from the PVL onward) is incorrect at least as regards Olga's first visit to Constantinople. As far as the place of Olga's baptism is concerned—Kiev or Constantinople—scholars still differ in their opinion. The incorrect date goes back to a miscalculation—or merely rough, approximate count—by James the Monk (Iakov Mnikh), the author of a memorial eulogy of Prince Vladimir, Pamiat' i pokhvala kniaziu rus'komu Volodimieru (in its extant form probably compiled only in the thirteenth century). He indicated that Olga had lived her last fifteen years as a Christian, the princess having died, as James himself correctly established, on 11 July 969. Recently, however, it has been sug gested on paleographic grounds that even the figure fifteen may be due to a misreading (or incorrect copying) and that James himself had indicated nine years as the time that had elapsed between Olga's baptism and her death, thus dating the former to the year 960, a date now favored by D. Obolensky on other grounds as well.

 Of all annalistic writings in Rus' only a few are known to have an indirect reference to what is possibly the correct date of Olga's baptism. One is the late (seventeenth century) so-called Hustyn Chronicle (Gustinskaia letopis'), which notes: "i kresti iu sam patriarkh Polievkt". The same Patriarch Polyeuctus (consecrated on 3 April 956) is also mentioned in connection with Olga's baptism in two other late (seventeenth century) chronicle compilations, the Kievan Synopsis and the Mazurinskii letopisets. These may echo earlier sources not reflected in the PVL. Since the reliable, precise dates for Olga's visits to the Byzantine emperor mentioned in the most detailed description of the two events, the second Book of Ceremonies (De caerimoniis aulae Byzantinae, chapter 15), authored—or at any rate edited—by Emperor Constantine VII Porphyro genitus (944-959), are Wednesday, 9 September, and Sunday, 18 October, but with no year indicated, scholars have speculated whether to date these visits to 946 or 957, the only potential years when these dates fell on Wednesday and Sunday, respectively.

Surprisingly and perhaps significantly, however, there is no mention in the emperor's account of the Rus' princess' baptism during her stay in Constantinople. Some researchers have suggested that Olga visited Constantinople in 957, but was subsequently baptized only in 959 in Kiev.49 Or they have left the question of the place of her baptism open. Another scholar, while at first also not taking a stand concerning the place and time of her conversion, preferred to date Olga's two audiences with the Byzantine emperor to 946, but subsequently opted for Olga's bap tism in Constantinople in 954/955.5'

O. Pritsak argues that Olga in fact visited Constantinople twice: in 946, when she was received by the emperor on Wednesday, 9 September, but was still a pagan, and in 957, when she saw the emperor on Sunday, 18 October, by now a newly converted Christian. The baptismal act itself would have been administered by Patriarch Polyeuctus just a day or so before. According to Pritsak, the first trip to Byzantium was apparently prompted mostly by the need to reconfirm the stipulations of the 944 agreement concluded in behalf of Prince Igor, her husband, slain the following year (945). Her second visit, during which she, in a private ceremony, would have become a Christian (and in that capacity, herself of Varangian stock, joined that portion of the Varangian-Rus' com munity in Kiev which already was converted), is not to be seen, so Pritsak reasons, as in any way inconsistent with her soon-to-follow embassy to the German king, Otto I. Olga is said to have returned to Kiev from Constantinople toward the end of 952   In early 958, she most probably discussed with her close advisers the possibility of introducing Christendom on a large scale in Rus'. She then could have dispatched her envoys to Frankfurt-am-Main in the late fall of that same year as they arrived at Otto's court by the early summer of 959. At that time, the Byzantine ruler, Emperor Constantine VII, maintained friendly relations with Otto I, whom he greatly admired. And after the official peace of the Church had been proclaimed in 920, the schism between an Eastern and a Western Church, clearly felt to have existed in Photius's days—in the second half of the ninth century—had for the time being been averted. According to Pritsak, "Olga was baptized in October 957 in Constantinople by Patriarch Polyeuctus. This was a personal, private conversion. When Olga later wanted to baptize her entire realm, she turned to the professional missionaries of Otto I, following the advice of the Byzantine emperor Constantine VII. The eventual failure of this attempt, despite Otto's great interest in eastern missionary activities, may well have led to, or sped up, Olga's dismissal from power by her son Sviatoslav, who resisted her urgings to turn Christian.

Concerning Olga's mission to King (and since 962, Emperor) Otto I, we read in the so-called Lothringian Chronicle, compiled by the anonymous continuator of Abbot Regino of Prum, usually identified with Adalbert of Trier, who subsequently became the first archbishop of Magdeburg: "Legati Helenae reginae Rugorum [Russorum, H.B.], quae sub Romano imperatore Constantinopolitano baptizata est, ficte, ut post claruit, ad regem venientes episcopum et presbiteros eidem genti ordinari petebant." Helena was the name Olga had assumed in baptism, presumably in honor of the mother of Emperor Constantine I the Great, Saint Helena, and/or as a gesture of courtesy toward the ruling emperor, Constantine VII (Porphyrogenitus), whose spouse's name was also Helena. The mention of Romanus II rather than of his father, Constantine VII, is remarkable insofar as Romanus died in March of 963, whereas the annalistic entries in Regino's continuator, Adalbert, run through 967. Still, this apparent inaccuracy may perhaps be explained by the fact that Romanus II (b. 939) was accorded the title of coemperor, basileus, as early as 945, i.e., prior to the death of Constantine in 959. However, this problem is resolved if we accept Obolensky's new date for Olga's baptism, the year 960, when Romanus II was sole emperor. As is known, Otto I responded to Olga's request favorably by having the monk Libutius consecrated missionary bishop to Rus'. Yet, for some reason he was first detained and then suddenly died in early 961. As his replacement the aforementioned Adalbert of Trier was selected to take on the task of going to Kiev. He did leave for Rus' but returned the following year, 962, his mission having failed. As Pritsak indicates, Adalbert's entry for 959 was probably written between late 962 (when he returned from Rus')—hence his aside-- ut post claruit—and mid-March of 963, when Emperor Romanus II, identified as the current ruler of Byzantium, died. Olga is further said to have founded the Church of the Holy Trinity in her native town of Pskov and to have had a chapel built at Askold's gravesite in Kiev. Tradition, moreover, has it that a church already existed in Novgorod in Olga's time.  The reasons for the failure of Adalbert's mission are not entirely clear. Nor do we know whether Olga's being removed from power by her pagan son Sviatoslav was a direct consequence of her failure, as well as the German bishop's, to convert Rus', or whether that failure itself was prompted by the political takeover in Kiev. Be this as it may, Sviatoslav's ten-year rule (962-972) marked a setback for Christianity and yet another reversion to paganism, even if we can assume that a Christian, still predominantly Varangian, community continued to exist in Kiev, though now under less favorable conditions.