During WW1 much of the Orthodox population fled to the east - so called Bezhenstvo:
https://uk-m-wikipedia-org.translate.go ... x_tr_hl=pl
Lucjusz Dura in his "Map of Polish population" has for Bialystok Oblast as of year 1916:
https://polona.pl/item/mapa-rozsiedleni ... o:metadata
County Sokolka - 71.0% Polish
County Białystok - 50.2% Polish
County Bielsk - 39.3% Polish
Total for the Oblast - 51.3% Polish
I'm sure that by 1939 this percent of ethnic Poles in the area increased even further.
The Russian census of 1897 was - according to all Polish authors who analyzed it - falsified in a an anti-Polish way.
Lots of Poles were counted as Catholic Belarusians or even Catholic Russians in that census. In reality, virtually all (at least the vast majority) of Slavic Roman Catholics in North-East Poland and Belarus identified as Poles. Belarusian-identified Catholics were a rarity.
Check e.g. the 1897 census for Sokołka County - 69.3% Roman Catholics and only 1.2% Poles - obvious falsification:
https://datatowel-in-ua.translate.goog/ ... x_tr_hl=pl
In case of Bialystok County, the scale of falsification is less severe - the gap between Catholics vs. Poles is smaller:
And in case of Bielsk County there is almost no falsification - because they didn't have to do it to achieve majority:
[the number of Slavic Roman Catholics is in line with the number of Poles in this case]
But the best formula to count Polish-identified people in the Kresy is to count all of Slavic Roman Catholics as Poles.
Even according to modern research (published in 2000) as many as 95% of Roman Catholics in the Diocese of Grodno in Belarus (so roughly the same historical region as the one we discuss here) declare that they have ethnically Polish ancestors. It is this study:
Even in Eastern Belarus - in the Archdiocese of Minsk-Mogilev - still 73% of Roman Catholics declare Polish ancestry.
There is also another similar study from year 2003 which basically confirms all of these findings of the 2000 study.
There are words which carry the presage of defeat. Defence is such a word. What is the result of an even victorious defence? The next attempt of imposing it to that weaker, defender. The attacker, despite temporary setback, feels the master of situation.