Complex sentence: On 9 May 1993 members of "Convicts' Battalion" were involved in siege of eastern part of Mostar, they intensively shelled the city and prevented the arrival of humanitarian aid.
Split into simpler sentences: On 9 May 1993, members of the "Convicts' Battalion" were involved in the siege of eastern Mostar. They intensively shelled the city and prevented the arrival of humanitarian aid.