Complex sentence: Sam Johnson was sent to collect the police pack horses so they could start in pursuit of Patrick Kenniff however on his return he found Doyle, Dahlke were nowhere to be seen and he was chased by the Kenniffs as he fled for help.
Split into simpler sentences: Sam Johnson was sent to collect the police pack horses so they could start in pursuit of Patrick Kenniff. However, on his return, he found Doyle and Dahlke were nowhere to be seen, and he was chased by the Kenniffs as he fled for help.