National Unity Day (Belarus)

The Peace of Riga, signed on 18 March 1921, divided the disputed territories between Poland and Soviet Russia and determined the Polish–Soviet border for the rest of the interwar period.

After that the territories east of the Bug River (known in Poland as the Eastern Borderlands) were incorporated into the (BSSR and USSR (Byelorussian and Ukrainian Soviet Socialist Republics).

[2] Belarusian historian Ales Kirkevich [be] reminded about the Day of Liberation of Belarus from White Poles [be], celebrated as a major holiday in BSSR from June 11 until 1939.

[6] Belarusian politologist in emigration Arciom Szrajbman argues that the pro-Soviet and pro-Lukashenka forces wanted this celebration to be re-established earlier, but probably Lukashenka hoped to maintain good relations with Poland and did not do this.

The first date was September 17, the second one was November 14, 1939, when the law on the admission of Western Belarus to the Byelorussian Soviet Socialist Republic was signed at an extraordinary session of the BSSR Supreme Council.

[8] On June 8, 2021 The Ministry of Foreign Affairs of the Republic of Poland issued a statement with a strong protest and described this act as "the glorification of Soviet heritage and an attempt to cut Belarus off from its true roots".