Original sentence: During the Great Sejm, he organized the confederation of 141 cities and towns and was at the forefront of demanding the the fuller representations and enfranchisement of the burghers in the Polish Sejm; notably, he helped organize the Black Procession on December 2, 1789 (a march of burghers who delivered a petition to the king)
Edited sentence: During the Great Sejm, he organized the confederation of 141 cities and towns and was at the forefront of demanding the fuller representations and enfranchisement of the burghers in the Polish Sejm; notably, he helped organize the Black Procession on December 2, 1789 (a march of burghers who delivered a petition to the king)