The Cowboys
(1972)

Will Andersen (John Wayne) is a Montana cattle rancher who needs to move hundreds of cattle to market.  The men he hired for the cattle drive desert him, to run off to the gold rush.  Will hires a group of school boys to handle the cattle drive with him.  Will teaches these boys to be men, and to be cowboys.

Asa Watts (Bruce Dern) wants to hire on for the cattle drive.  Asa is a fugitive, and Will realizes that Asa is violent, and a liar.   Will refuses to hire him, but Asa and his gang follow the cattle drive.

Asa and his gang take them by surprise.  Asa kills Will.  The boys continue the cattle drive on their own, and get the cattle to market.  On the cattle drive, their is a black cook, Jeb Nightlinger.  Asa and his gang catch Nightlinger and are planning to lynch him.  The boys surprise the gang.  The boys rescue Nightlinger, killing Asa.

Thanks Joseph C!