"A word is necessary about the flag, because officially jäger regiments were not permitted a flag at all."
Correct.
"However it is known that this rule was not entirely observed as the flag of the Life Guard Jäger Regiment was captured at Austerlitz"
No correct.
At Austerlitz, the Life-Guard Jäger battalion of 4 companies (15 officers and about 375 other ranks – not yet of regiment size) perfomed quite well in a very heavily out-numbered defense of Blaziowitz diring the mid to late morning. In the afternoon, they were then ordered into and behind Krenowitz, where they helped cover the Allied retreat. Their commander (from 7.III.1805), a French emigré, colonel (from 31.V.1801) vicomte Emmanuel de Saint-Priest (1776-1814) was awarded the Order of Saint-George 4th-class "In recognition of outstanding courage and bravery shown against the French army in the battle of 20 November [O.S.] at Austerlitz."
All 15 other officers in the battalion were also decorated :
--- awarded Saint-Vladimir 4th class : 1 – for the deputy commander, colonel Yakov Alekseyevich Potemkin
--- awarded Golden Sword for Bravery : 5
--- awarded Saint-Anne 3rd class : 9
Of the officers, 5 were wounded, of which 1 died later and 1 (an adjudant making a report) was missing and taken prisoner unconcious.
Of the ~375 other ranks, 47 were killed or mortally wounded.
The battalion did not lose a flag.
The first flags ever issued to the Life-Guard Jäger were three "Guard Saint-George" flags issued on 24 December 1814. The dark half-cormers shown below were very dark green, not black.
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No Russian Jäger regiments were awarded any flags, not even Saint-George flags, in the period. When a Saint-George award was made, a pair of inscribed silver trumpets with Saint-George ribbons (and 2 over-complement musicians) were given instead.
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Overview of Russian Jäger units from TMP link
A long list of regiment numbers is a little hard to individualize. So, expanding a post on TMP from April 2012 by Seroga, let me try to give a little bit of the details by unit.
There were two guard jäger formations in the Russian service.
-- Лейб-Гвардии Егерский полк – formed 1796 as a battalion, from the jäger detachments in the guard heavy infantry formations and the demonstration jäger company in the Gatchinskiy troops under Pavel's command, expanded by individual selection of soldiers to a regiment in 1806, Saint George flags for 1812, silver trumpets for Kulm
-- Лейб-Гвардии Финляндский полк – raised in 1806 initially as the militia battalion from the Emperor's own properties, held in service for excellent perfomance in combat, expanded by individual selection of soldiers to a regiment in 1811, Saint George flags for 1812, silver trumpets for Leipzig
Next are the senior army jäger formations, with direct linkage back to the initial formation of jäger detachments in the 1760's. They maintained their regional characteristics at least to 1803 (recruited from and located in the named regions). These units were also issued rifles for at least the NCO's and 12 markmen, and often more. They all took their indicated name by 1803. Virtually all of these units that served against the French were given one or more honorific distinctions. Regiments were 3 battalions in 1812, and had been established at the same size as heavy infantry regiments since 1806. In 1812, there were 2 jäger regiments per division. Beginning after Borodino, in several cases the two regiments of a division would be consolidated into the senior regiment, and the cadre of the junior regiment sent back to refit and take in replacements. The consolidations in the 2nd Western Army are noted below for the 41st, 42nd and 50th Jager.
-- [1-й Егерский полк] – first formation, from Finland jäger corps of 1785, disbanded after substantial losses from sickness in the descent on Holland led by the Duke of York …. the then-exisitng 19 other regiments were each promoted by one number, and a new 20th regiment was formed
-- 1-й Егерский полк – from Finland jäger corps of 1785, St. George award for 1807, imperial family member as "shef" from 1811, issued Russian obr. 1808 muskets, "For excellence" shako badge award for 1812, promoted to grenadier-jäger in 1814
-- 2-й Егерский полк – from Finland jäger corps of 1785, silver trumpet award for 1814, silver trumpt award from the Dutch government
-- 3-й Егерский полк – from Estonia jäger corps of 1790, St. George award and grenadier march music for 1807, issued purchased British Brown Bess muskets, promoted to grenadier-jäger in 1814
-- 4-й Егерский полк – from Estonia jäger corps of 1790, silver trumpet award for 1807, grenadier march music for 1808, issued Russian obr. 1808 muskets
-- 5-й Егерский полк – from Estonia jäger corps of 1790, St. George award 1807, grenadier march music for 1808, issued purchased British Brown Bess muskets, "For excellence" shako badge award 1812
-- 6-й Егерский полк – from Livonia jäger corps of 1785, allowed grenadier march music for 1799 (where it was largely rifle armed), silver trumpet award for 1805, the regiment is closely associated with prince Bagration who had led the regiment earlier in his career and then under whom the regiment served for many years and with the comte Emmanuel de Saint-Priest who was also a long-time deputy to the prince Bagration
-- 7-й Егерский полк – from Livonia jäger corps of 1785, allowed grenadier march for music 1799 (where it was largely rifle armed), silver trumpet award for 1812
-- 8-й Егерский полк – from Livonia jäger corps of 1785, silver trumpet award for 1813, promoted to grenadier-jäger in 1814
-- 9-й Егерский полк – from Ekaterinoslav jäger corps of 1787, assigned to the Caucasus
-- 10-й Егерский полк – from Belarus jäger corps of 1785, "For excellence" shako badge award for 1812-1814
-- 11-й Егерский полк – from Belarus jäger corps of 1785, St. George award for 1812-1814
-- 12-й Егерский полк – from Bug jäger corps of 1785, remained on the Danube through 1812 and joined operations against the French only in 1813
-- 13-й Егерский полк – from Bug jäger corps of 1785, "For excellence" shako badge award for 1814
-- 14-й Егерский полк – from Tauride (Crimea) jäger corps of 1785, "For excellence" shako badge award for 1812, promoted to grenadier-jäger in 1814
-- 15-й Егерский полк – from Tauride (Crimea) jäger corps of 1785, assigned to the Caucasus
-- 16-й Егерский полк – from Kuban-Caucasus jäger corps of 1784, assigned to the Caucasus
-- 17-й Егерский полк – from Kuban-Caucasus jäger corps of 1784, assigned to the Caucasus, promoted to karabiniers in 1816
-- 18-й Егерский полк – from 1st Siberian jäger battalion of 1775, issued Russian obr. 1808 muskets
-- 19-й Егерский полк – from 2nd Siberian jäger battalion of 1775, silver trumpet award for 1814, "For excellence" shako badge award for 1814
-- 20-й Егерский полк – from Olonets jäger battalion of 1790, silver trumpet award for 1807, issued purchased British Brown Bess muskets, allowed grenadier march music for 1812, "For excellence" shako badge award for 1812, promoted in seniority to 1st Jäger in 1815, the regiment is associated with the rather famous jäger commander Karl Ivanovich Bistrom-1 who led the regiment until his promotion to command the Life-Guard Jäger in 1809
The following units were formed from August 1805 to August 1806. They were raised by assigning 4-8 companies from an exisiting unit of musketeers or jägers (jäger cadres are noted below) and filling out with 4-8 companies of recruits for a total of 12 companies. Rifles for NCO's and marksmen were issued, usually the new Russian obr. 1805 jäger rifle.
-- 21-й Егерский полк – raised at Uglich near Yaroslvl' with a cadre of 4 companies from 2nd Jäger, issued purchased British Brown Bess muskets, allowed grenadier march music for 1812, promoted in seniority to 3rd Jäger in 1815
-- 22-й Егерский полк – cadre of 6 companies from 11th Jägers, issued purchased Brown Bess British muskets,remained on the Danube through 1812 and joined operations against the French only in 1813
-- 23-й Егерский полк – cadre of 8 companies from 18th and 19th Jäger, issued M1808 muskets for 1812, silver trumpet award for 1813
-- 24-й Егерский полк – issued Russian obr. 1808 muskets for 1812, silver trumpet award for 1812
-- 25-й Егерский полк – issued purchased British Brown Bess muskets, silver trumpet award for 1812
-- 26-й Егерский полк – issued purchased British Brown Bess muskets, silver trumpet award for 1812, "For excellence" shako badge award for 1813, promoted to grenadier-jäger in 1814
-- 27-й Егерский полк – assigned to Serbia garrison in 1812
-- 28-й Егерский полк – St. George award for 1812-1814
-- 29-й Егерский полк – promoted to grenadier-jäger in 1814
-- 30-й Егерский полк – issued Russian obr. 1808 muskets
-- 31-й Егерский полк – issued captured Swedish long arms, assigned to Petersburg garrison in 1812
-- 32-й Егерский полк – cadre of 4 companies from 18th Jäger, St. George award for 1812-1814
The following units were formed in 1810. They were converted from existing musketeer regiments of varying seniority. Since 1808, rifles were no longer included in the establishment of jäger regiments (it is unclear how many rifles were actually returned from the first 32 regiments, if any), and so were no longer being issued. Some of these units entered the campaign of 1812 with some degree of musketeer/infantry distinctions, such as white belting.
-- 33-й Егерский полк – ex-Senate battalion/regiment (picked security troops for the Russian Senate in Petersburg), issued Russian obr. 1808 muskets, silver trumpet award for 1814, the regiment is closely associated with the second of the Bistrom brothers, Adam Ivanovich who led the regiment until his promotion to command the Life-Guard Pavlosvskiy regiment in 1815
-- 34-й Егерский полк – issued Russian obr. 1808 muskets
-- 35-й Егерский полк – issued Russian obr. 1808 muskets, assigned to Arkhangelsk garrison in 1812
-- 36-й Егерский полк – issued purchased British Brown Bess muskets
-- 37-й Егерский полк – issued purchased British Brown Bess muskets
-- 38-й Егерский полк – issued Russian obr. 1808 muskets
-- 39-й Егерский полк – issued Russian obr. 1808 muskets, silver trumpet award for 1812-1813, "For excellence" shako badge award for 1814
-- 40-й Егерский полк – issued purchased British Brown Bess muskets
-- 41-й Егерский полк – allowed grenadier march for music 1799 (then a musketeer regiment), consolidated into 6th Jäger after Borodino
-- 42-й Егерский полк – consolidated into 5th Jäger after Borodino
-- 43-й Егерский полк – assigned to Serbia garrison in 1812
-- 44-й Егерский полк – "For excellence" shako badge award for 1814
-- 45-й Егерский полк -
-- 46-й Егерский полк – issued Russian obr. 1808 muskets, assigned to the Caucasus, promoted in seniority to 17th Jäger in 1816
The following units were raised from various infantry garrison formations in January 1811. The three units that faced the French performed very well. Issue of the Russian obr. 1808 musket was typical. The 49th and 50th Jäger were in Neverovskiy's newly formed 27th infantry division, which Napoléon rather famously under-estimated as a formation of raw recruits and invalids.
-- 47-й Егерский полк – assigned to Petersburg garrison in 1812
-- 48-й Егерский полк – issued Russian obr. 1808 muskets, silver trumpet award for 1812
-- 49-й Егерский полк – St. George award for 1812, St. George award again for 1814, "For excellence" shako badge award for 1812-1814
-- 50-й Егерский полк – silver trumpet award for 1812, consolidated into 49th Jäger after Borodino
The following units were raised from April 1813 from the 2nd Reserve and 4th Replacement or Recruit battalions of regiments that had formed the Danube Army at the start of 1812. A fair number of captured French muskets were initially issued to these units, for want of the much more favored Russian obr. 1808 and British Brown Bess muskets. When the grenadier-jäger were renamed and renumbered as karabiniers in 1815, in some cases their old numbers and seniority were assigned as a distinction to other regiments, as noted above. The following units were then re-numbered to fill-in the missing numbers.
-- 51-й Егерский полк – renumbered 8th Jäger in 1815
-- 52-й Егерский полк – renumbered 14th Jäger in 1815
-- 53-й Егерский полк – renumbered 20th Jäger in 1815
-- 54-й Егерский полк – renumbered 21st Jäger in 1815
-- 55-й Егерский полк – renumbered 26th Jäger in 1815
-- 56-й Егерский полк – renumbered 29th Jäger in 1815
-- 57-й Егерский полк – assigned ot the Caucasus, renumbered 46th Jäger in 1816
The following units were opolchenie or volunteers formed for the 1812 campaign, and not intended to remain part of the regular Army. But they turned out to quite good light infantry and many were retained until the end of the 1814 campaign.
-- Vologda & Olonets opolchenie – each 1 battalion size, raised from hunters and forresters, included as the 17th and 18th cohorts of the Petersburg opolchenie, issued some Russian obr. 1805 rifles, retained in service all the way to Paris
-- Grand Duchess Ekaterina Pavlovna Jäger battalion – over-sized battalion raised from residents of Her Highness' rural and forest estates in the Tver region, armed with Russian obr. 1805 rifles and Russian obr. 1808 muskets, retained in service all the way to Paris
-- Russo-German Legion Jäger company – formerly the 3rd company of the East Prussian Jäger Battalion, captured/changed sides as a unit in August 1812, re-equipped with 23 British Baker and the remainder Russian obr. 1805 rifles, later expanded and transferred to the Prussian service
-- Perm & Vyatka opolchenie – 1 battalion size, raised from hunters and forresters, included in the Kazan opolchenie, served later as scouts for the 3rd Western Army, retained in service into 1814
-- Courland Marksmen corps – regiment size, formed from hunters and forresters, used as scouts and partisans, issued some Russian obr. 1805 rifles
-- Livonia Marksmen corps – regiment size, formed from hunters and forresters, used as scouts and partisans, issued some Russian obr. 1805 rifles
"Honorable mention" ….
-- Saint-Persburg opolchenie, 1st cohort – battlaion size, called the "Merchants" or the "Philistenes" as they were volunteers drawn from the Petersburg middle class and foreign residents, with experiened senior officers, armed with Russian obr. 1808 muskets, actually performed markedly well as skirmishers in support of the 1st separate corps operating in defense of the approaches to Petersburg and the north flank of the main Russian army in 1812
The following were called "jäger", but were light infantry mostly in name only.
-- Moscow opolchenie – 3 jäger regiments
-- Ryzan opolchenie – 2 jäger regiments
-- Tula opolchenie – 1 jäger regiment
-- Kaluga opolchenie – 1 jäger battalion
-- 1st & 2nd Finnish Jäger regiments – each only 2 battalions (not the usual 3), volunteer formation, mostly ex-Swedish veterans, garrisoned Russian Finland, some light infantry capability
-- 3rd Finnish Jäger regiment – also 2 battalions, 1 each in Vyborg and Petersburg garrisons, recruited in the Vyborg region by conscription