Original: A decision was reached in the Central Lithuanian Parliament on February 20, 1922, to return the whole area to Poland, with Vilnius becoming the capital of the Wilno Voivodship.
Simplified: On February 20 1922 after an elections, the whole area was attached to Poland, with the city as the capital of the Wilno Voivodship (Wilno being the name of Vilnius in Polish).