Complex sentence: Furthermore, he signed arrests of oppositional deputies, who were sent to Brest Fortress after the dissolution of the Sejm (August 30,1930), and participated in the organization of the so-called Brest Election.
Split into simpler sentences: Furthermore, he signed arrests of opposition deputies, who were sent to Brest Fortress after the dissolution of the Sejm (30 August 1930). He then participated in the organization of the so-called Brest Election.