The information for the depictions of these flags comes from a paper "Boiovi prapory kozats'koho viis'ka (seredyna XVII st.)" [FLAGS OF THE UKRAINIAN COSSACK ARMY IN THE MIDDLE OF THE SEVENTEENTH CENTURY, in Ukrainian], in Iaroslav Isaievych, Ukraina Davnia i Nova, Lviv, 1996, 44 - 49. First published: Ukrainskyi Istorychnyi Zhurnal, 1963, 1, 85-87. Professor Isaievych is president of the International Association of Ukrainian Studies and director of the Lviv-based Krypyakevych Institute of Ukrainian Studies of the National Academy of Sciences of Ukraine. The original source material was obtained from the Radzivill family archives (these particular documents were stored in the Manuscript Section of the archives of the State Public Library of M Y Saltikova-Shchedrina in St Petersburg).
When Janusz Radzivill led the Lithuanian army in its advance on Kyiv in 1651 during the Cossack Rebellion or the Liberation War (depending on which side of the border you were on), he had with him a Dutch artist and engraver, Adam van Vesterfeld. This artist captured scenes of Kyiv and the army, including sketches, with detailed information on the colours, materials used and methods of construction, of standards carried by the Chernihovski and Kyivski Cossack Polks. These were Polks (either regiments or brigades depending on the size of the province) of the Left Bank, or the Ukrainian, Cossacks
Flags 1 - 12 are flags of the Chernihovski Polk and the Flags 13 - 26 are from the Kyivski region (NB - some flags could be attributed to local Cossacks, the Kyivski provincial militia or guilds, specifically flags 13, 15 and 19 which have a corrupted representation of the crossbow from the Kyivan coat of arms).
No dimensions are specified for the flags but, since later (1700s) Cossack flags are noted as being of a large size (1706 cavalry standard was 176 cm on the flagstaff, with a width from 99 to 264 cm) compared to contemporary European flags, it would be safe to assume that these flags were large.
I have extrapolated in certain cases where information has not been provided, this includes flag no. 8 where no colour is provided for the body of the flag. I have depicted this flag with a sky blue body but it could equally be a grey or yellow body. In Flag 4, no colour is specified for the cross, so I have chosen to depict this as white, in line with the border and stars.
Flag no. 17 is specifically described in the main body of the text as a Polish style flag of red with a white eagle and crown. In the short descriptions of the flags it is noted as a black eagle. The Ukrainian words for red and black are superficially similar, so I have assumed that the main body of text is correct and chosen to depict this flag as a Polish flag ie red with white decorations. Incidentally this flag is described as either a trophy from the campaigns of 1648-49, or a previous gift from the Polish crown.
Flag no. 7 is interesting as it closely resembles contemporary Muscovite flags. No specific mention is made of this flag in the text but again this could be either a trophy, gift or of local manufacture.
Flag no. 25 is specifically described as being attached to the 'insignia' of the Hetman, no specific details are provided but it is likely that the 'insignia' is a Polish style bundchuk. The use of a Polish style knight's cross instead of a Greek cross, as on the other flags, is also interesting.
Plate 1 - Flags of the Chernihovski Polk
Plate 2 - Flags of the Kyivski Region