Complex sentence: According to the Brigade Operation Report, however, Kelly's column at Troitsa was successful at first but then withdrew as he considered the position insecure and was having difficulty obtaining ammunition supplies; when ordered to resume the attack, Kelly declined to do so.
Split into simpler sentences: According to the Brigade Operation Report, Kelly's column was successful at first but then withdrew as he considered the position insecure and was having difficulty obtaining ammunition supplies. When ordered to resume the attack, Kelly declined to do so.