Complex sentence: He was the key figure in IRA contacts with the Soviet Union during the late 1920s and in 1927, he attended the first International Congress of the Friends of Soviet Russia (FOSR) in Moscow.
Split into simpler sentences: He was the key figure in IRA contacts with the Soviet Union during the late 1920s. In 1927 he attended the first International Congress of the Friends of Soviet Russia (FOSR) in Moscow.