Complex sentence: In July, the guns were transferred to yachts sailed by Childers and Conor O'Brien, and then landed in Howth, Dublin, by Childers and Kilcoole, County Wicklow by O'Brien.
Split into simpler sentences: In July, the guns were transferred to yachts sailed by Childers and Conor O'Brien, and then landed in Howth, Dublin. By Childers and Kilcoole, County Wicklow by O'Brien.