The background of the Russian General Rodion Baur (Родион Христианович Баур/Бауэр/Боур) seems most unclear. According to Russian Wikipedia he belonged to a wellknown Swedish noble family which had settled in Germany (perhaps the author means the "Bonde" family? Bonde is Swedish for "peasant" - or in German "Bauer") He had entered a Swedish regiment of dragoons in Livonia and had at the time of the outbreak of the Great Northern War reached the rank of captain. During the siege of Narva, the article continues, he suddenly switched sides and deserted to the Russian army. The German Wikipedia article for some strange reason calls Baur "Christian Felix", claims that he at the beginning of the Great Northern War served in the Prussian army, then switched to the Swedish because he had fought a duel and finally went over to the Russians.
Some of these unclear points can be cleared up directly. There is no doubt that Baur had served in the Swedish army in Livonia. Carl Gustaf Skytte, the commander of the Dorpat garrison, in his journal describes how Baur on 29 June 1704, after having seen Cavalry Captain Holden during a skirmish outside town, sent word to Dorpat asking to be allowed to talk to Holden. When Holden came out Baur showed him great courtesy because he had once been a private in the company where Holden had been a Lieutenant. To the journal there is also attached a copy of a letter from Bour to Skytte in which the former writes: "Bitte meinen gewesenen Lieutenant itzigen Rittmeister Hollde unbeschwert zu grüssen...". This places Baur firmly in Drottningens Livregemente till häst, a cavalry regiment stationed in Estonia and Livonia in which Erik Johan Holden was a Lieutenant between 1679 and 1695. There are not too many muster rolls preserved for this regiment (at least not in Sweden), but the one from 1690 puts Holden in Otto Zöge's company. Unfortunately the pages are very heavily damaged and some names missing entirely.
So how about Baur and the start of the Great Northern War? Well, on 20 August 1700 Otto Vellingk wrote to Charles XII from Rujen (Latvian Rūjiena) about recent developments. According to Vellingk an enemy cavalry captain by the name of Bauer had arrived a couple of days earlier (According to Leonhard Kagg's diary Baur came on the 13th). Baur had explained that he had fought a duel, killed his opponent and been forced to flee. Baur claimed that King Augustus was weakly guarded and seems to have suggested that a strong Swedish detachment from the Riga garrison would have every chance of capturing him and destroy the Saxon camp. Vellingk had immediately informed Dahlbergh of this and also sent the King a detailed list of the Saxon army - based on Baur's testimony. The matter is very reminiscent of Johan Gummert's action at Narva a few weeks later, when he upon arrival suggested that a a few hundred Swedish soldiers led by Gummert could capture the Czar.
Apparently Vellingk sent Baur to Narva, because it was there that the latter engineered a most curious escape (in the manuscript Utföhrlig berättelse it's stated that Baur arrived in Narva a few days before the siege started) On 28 September 1700 some gentlemen from Narva and Baur had met in the house of the merchant Samuel Meux, where they ate a dish based on celery. During their conversation one of them said that celery grew just outside the town gates and it was decided to ride out the following day to pick some more. During this expedition Baur, who was on horseback, suddenly rode off at great speed towards the Russian camp.
Riksarkivet, Skrivelser till Konungen, Karl XII, vol. 29
Riksarkivet, M 1373 (Utförlig berättelse, huruledes- - -enkannerligen fästningarne Narwa och Ivangorod - - - belägrade blifvit av Zahren av Muscou)
Krigsarkivet, Rullor 1620-1723, vol. 1690:21
Kagg, L., Leonhard Kaggs dagbok 1698-1722. - Stockholm, 1912
Ramsay, J., Narvas rådsturätts protokoll för d. 1 okt. 1700 angående generalen R. F. Bauer // Historiallinen arkisto. XXVIII (1920). Tieteelisiä ilmoituksia. - P. 12-14.
Skytte, C. G., Öfversten och kommendanten Carl Gustaf Skyttes berättelse om Dorpats belägring 1704 // Karolinska krigares dagböcker jämte andra samtida skrifter.Vol. XI. - Lund, 1916. - P. 219-326
Christian Felix Bauer. http://de.wikipedia.org/wiki/Christian_Felix_Bauer (2013-06-29)
Баур, Родион Христианович. http://ru.wikipedia.org/wiki/%D0%91%D0%B0%D1%83%D1%80,_%D0%A0%D0%BE%D0%B4%D0%B8%D0%BE%D0%BD_%D0%A5%D1%80%D0%B8%D1%81%D1%82%D0%B8%D0%B0%D0%BD%D0%BE%D0%B2%D0%B8%D1%87 (2013-06-29)